- Mike and Lucy in Bittersweet Candy Bowl, during the old series.
- Dragon Tails. No matter how upset he gets when he learns that she's taken quite a liking to a French gargoyle named Jacques, Lemuel stubbornly insists that his penpal Firewing is not his girlfriend.
- Agatha Heterodyne in Girl Genius gets steamed if anyone suggests she and Gilgamesh Wulfenbach are lovers... at first. Later she just stammers flustered denials (usually to someone who would respond to screaming with a boot to the head). Her fangirling over his Death Ray working is entirely beside the point. Really.
Higgs: Uh—she—she ain't my Miss Zeetha, sir.Tarvek: Oh, heaven forbid. I'm sure you'd desert your post and hare off to save any green-haired amazon.
- Inverted earlier, when she's pretending to be someone's girlfriend, and has to stop herself from giving it away. "I NEVER! He's nnn-" " 'nnn'? As in NNNOT your boyfriend?" "...as in 'nice.' He's really nice."
- Abner starts to say this, but is corrected by Pix with a smooch.
- Agatha rants about this as she casually takes care of Castle Heterodyne's various defenses, which actually leads to it asking her to turn her death ray down.
- Violetta learns the dangers of it here.
- Airman Axel Higgs steadfastly denies that he cares about Zeetha.
Tarvek: You really are the best minion ever.Moloch: I am not her minion!.
- And of course parodied between Agatha and Moloch Von Zinzer, only the relationship in question is "minion".
- Used by Ash in Misfile here, not even she believes that though.
- Inverted later on, with an example of "you are not my girlfriend".
- Konstantin with Anya in Experimental Comic Kotone. See here.
- Played with in Friendly Hostility: Fox normally has no problem in referring to Collin as his boyfriend, but when Collin shows up while his coworker Derringer is pestering him about becoming buddies, he quickly rushes to loudly introduce him to Derringer as his "BEST FRIEND". Collin just as quickly walks off before he gets mad enough to do something he'll regret.
- Issac and Joy in Namir Deiter, though it's only by mutual agreement (and a boatload of issues) that they're not.
- Except they've recently been upgraded to Beta/Tertiary couple, after an argument while on a double-date (with different people).
- Shadehawk and Crossroad in Antihero for Hire, though with all the UST between them, some feel it's only a matter of time. The most notable example is here:Hector: Looks like your girlfriend's coming to the party.
Shadehawk: Ugh. You are such a depraved monster. Insinuating that she's my girlfriend, I mean.
- In The Inexplicable Adventures of Bob!, Bob frequently has to reiterate to his girlfriend Jean that there is nothing between him and the alien Princess Voluptua. Despite the fact that they have kissed. And that Voluptua is now stationed in Earth's solar system. And that she is a Stripperiffically-clad Head-Turning Beauty of the first order. Because Bob knows that she is in fact, under her disguise, a giant alien bug.
- Boris, the robotic spider in Bugs, has shouted more than once that a real spider with a keen interest in him is not his girlfriend.
- Zoe from Sluggy Freelance invokes this trope after several of her friends hold an intervention for her because they think she's dating Torg.
- Kitti and Sky in Divided Sky are both in denial of their feelings for each other, despite everyone else picking it up.
- A customer in Welcome to the Convenience Store, when asked about his female friend, said she was a "friendly woman person".
- Lance says this about Silvia in Shape Quest.
- xkcd demonstrates that this retort can be defeated by statistics
- Sequential Art give us Art and Kat's reaction to the suggestion they are a couple. The next strip shows more.
- In Gunnerkrigg Court Zimmy offhandedly refers to Jack as Antimony's boyfriend after she restores his sanity and explains what happened leading up to it. Antimony thanks her, but adds "Also; not my boyfriend." This sets up the latter Ship Tease in this strip. Maybe because after this adventure Two Strange Girls already knew his attitude.
- However, in the short term at least, this turns out to be true. Jack has a crush on Zimmy of all people, and Annie, at the time of making the aforementioned statement, held a hidden grudge against Jack. They're likely in for more teasing of that sort now, though, considering that as far as their classmates are concerned Jack publicly gave Annie a note and some of them saw them amiably chatting then going off on their own for a night. Of course, there's a nonromantic explanation for those, but others don't know that.
- Liu Wong and Fang Lin in How I Killed Your Master.
- Far Out There had Trigger and Layla both respond in this manner when Ichabod suggested they were a couple. They actually mean it.
- Then it happened again. Unfortunately, it was Trigger's crush who though he and Layla were an item.
- When Lemon and Lime first meet Alice in Evil Plan'' they immediately that she's Kinesis' girlfriend. Alice's words say no, but her expressions says differently.
- General Protection Fault has Patty laying it on a bit too thick about her not-boyfriend:Dwayne: That was quite an adventure you guys had. How's Dexter?
Patty: Argh! Not you too! Look, we are not dating! We made peace! That's it! Not seeing each other, not dating, not engaged, not getting married, not breeding! "Friends" is pushing the definition! We just aren't fighting anymore!
- Several people in Questionable Content refer to Angus as Faye's boyfriend or something similar before they are officially an item, but have admitted their mutual attraction. Faye denies this.
- Justin of El Goonish Shive insists vehemently that Elliot is not his boyfriend. He's telling the truth—Elliot is already taken and it wouldn't work out anyway.
- The Summer arc had Susan stating that Elliot isn't her boyfriend to a number of people when he decides to take a job at the same video store as her. Time will tell how this will go though.
- After the time skip to End Of An Era Part 2, it's become obvious that the two have become much closer and are mutually attracted. They've even specifically denied being a couple in several of their video reviews.
- The eponymous Sarab say this about Karin. In front of her. She does not take it well.
- In Blue Yonder, Lena's saying this produces a rather different effect, as she faces him down for claiming it.
- In Ears for Elves, Donny sees Tanna walking arm-in-arm with Rolan. Donny infers that Rolan must be her boyfriend, and finds this disgusting; Tanna protests madly. A while later, Donny tells Tanna that her new boyfriend isn't so bad after all; her reaction is to say that Rolan is not her boyfriend.
- In one story arc for Cheer!, Lita forces Alex (who is a girl, yes) to take her out to dinner to a steak house. She also forces Alex to go to the dinner wearing a nice suit. Cue Alex spending most of the evening telling the restaurant staff that she is not Lita's date and not a "sir".
- In Footloose, Jenny refers to Keti as Dan's girlfriend - she, Dan, and Iordan insist she isn't in unison, Keti and Dan being genuinely Squicked by the idea, and Iordan having a vested interest in Keti being single.
- In Homestuck, Terezi seems to inspire a lot of this. Karkat repeatedly denies having a "thing" with her when numerous other characters notice their bond, and Dave denies dating her when Karkat starts getting jealous.
- As far as Lisa and Ally of Sunstone are concerned; she is just the woman I live with, have lots of kinky sexy with, and spend most of my time with. This delusion is upheld by the characters so they don't have to question whether they are homoromantic or if the other reciprocates; but all their closer friends can see through it. They finally get the Relationship Upgrade at the end of the strip.
- Rhapsodies Paul and Nancy insist they are Just Friends... good friends
- In Housepets!, Zach uses this line when found in a compromising position with the wild possum Jess. In defiance of how the trope usually goes, she interrupts him and completely ignores the accusation; they're in a crisis situation. But a few hours later...
- In Avialae, every relative that sees Gannet and Bailey together assume that they're dating. This is not helped by Gannet's complicated hang-ups with relationships making him fine with doing everything with Bailey but calling their outings together "dates".Gannet: They think we're dating. This isn't going to help.Bailey: And we're not?Gannet: No.
- Manly Guys Doing Manly Things: Variant. Jones has serious commitment issues, and doesn't want to label her relationship with the Commander, even though they do all the normal couple things like spend major holidays together. The Commander, for his part, considers this a small price to pay for being in a stable relationship, and is quick to stop other people when they try to point out flaws in her logic.
- Never Satisfied: Seiji's reaction to Rin chiding him on inappropriately taking out his frustration with Sylas being annoyed with him.Rin: It's not [January's] fault your boyfriend's mad at—
Seiji: Buh— spuh— he's not my boyfriend!!
- Mage & Demon Queen: Velverosa insists Malori means nothing to her... while her tail is visibly wagging. Her underlings just want her to finally admit her attraction.
She Is Not My Girlfriend / Webcomics