This is a variation on Accidental Pervert, in which the accidental part is not so accidental.
This trope generally comes in two variations. First, are instances where someone intends to initiate romantic/sexual contact with a significant other or romantic interest, but touches the wrong person. This will usually be because someone looks similar to the real target of affection.
In other instances, a character actually means to sexually harass someone (usually a Ms. Fanservice character), but for the same reasons as above, picks the wrong person (usually a gonk or otherwise stern and/or unattractive character).
- The classic Grape Nuts commercial where a young man grabs his girlfriend's mother's butt in the swimming pool:
"Mrs. Burke? I thought you were Dale!"
- A Wendy's ad has a guy going to a restaurant where he meets an attractive lady at the drive-through window. Finally, he asks her out without looking at the window—but she's been replaced by a middle-aged man.
- A Sequential Art example: In one story by Wilhelm Busch. After having received a letter by Julchen (the object of affection) encouraging him, he enters her house at night. She intentionally misled him however, and he ends up in the room of her aunt, who is NOT pleased. (Neither is he, but for other reasons.) Confusion ensues.
- In the The Familiar of Zero anime, Louise gets into the bed that she, Saito, and Siesta share. The problem? Well, she ends up being kissed by Siesta, who had mistaken her for Saito.
- One Piece: Zoro and Sanji almost get an Accidental Kiss moment when they're waking up one morning and Sanji mistakes Zoro for Nami.
- In She's the Man, Olivia falls in love with her classmate "Sebastian", unaware that it's actually his sister Viola pretending to be him. One night she surprises her object of affection with a kiss... unaware that it's actually the real Sebastian, who has no idea who this infatuated girl is.
- In The Big Easy after a night of lovemaking, Anne mistakes Bobby McSwain for his brother Remy, coming up behind him and pinching his ass. The brothers aren't all that identical, but given that she had no reason to expect any other man in the house and her view of Bobby was mostly of his rear end as he bent to rummage through the fridge, it is perhaps an understandable mistake.
- The Film of the Book of The Girl, the Gold Watch and Everything. Kirby Winter goes to his brother's house and goes to sleep in his bed. His brother's girlfriend Bonny Lee Beaumont slips into the bed, thinks he is his brother and starts to make love to him.
- In the 1947 short "the Brideless Groom" starring The Three Stooges, Christine McIntyre's character mistakes Shemp Howard for someone else. Christine is expecting her cousin, Basil, and thinking that Shemp is him, starts kissing him affectionately. When she gets a phone call revealing that her visitor is NOT her cousin, she really unloads on Shemp, resulting in a No-Holds-Barred Beatdown.
- In Think Big, Rafe's waitress girlfriend drags the man she thinks is Rafe into a back room to have sex with him. Unfortunately, it's actually Rafe's twin brother Victor, who reveals the mistaken identity as soon as he's allowed to get a word in edgewise. She then proceeds to slap him for this misunderstanding.
- Played for laughs in one of the Beethoven movies where the father thinks he's cuddling his wife and sweet-talking her; only when she comes in and asks who he's talking to does he realize the dog's in his bed.
- Invoked in a folktale involving a Court Jester and/or The Trickster of the teller's culture wherein he offends the King, and is told he will be executed unless he can apologize in a way wherein the apology is worse than the offense. He achieves this by groping the King from behind and saying, "Sorry, I thought you were the Queen."
- In Dragon Bones, there is a pair of identical twins, one of whom (who is a ladies' man) has an affair with a woman. His rather shy twin brother is very embarrassed when his brother's lover accidentally pinches his buttocks.
- In one Guy de Maupassant story translated as "A Bad Error", a man is in a relationship with a woman who wanted it to remain platonic until they knew each other better, and they both take a vow of celibacy in the meantime. He doesn't stick to his vow, and starts up an affair with a beautiful maidservant of the woman, who had told him she was built similarly to her mistress. Things end badly when, thinking it is the maidservant, he goes up to the woman and lifts up her skirts and kisses her on the behind.
- In an episode of Modern Family, Phil has a disastrous first meeting with his daughter's college roommate - he grabs her butt, thinking that she was his wife.
- In one episode Everybody Hates Chris, Julius goes in the bathroom and grabs what he thinks is Rochelle's butt only for it to be their new neighbor.
- In an episode of Dr. Ken, he tries to teach his daughter the danger of alcohol by getting roaring drunk. Then he embarrasses her at a party. After she runs out he puts his arm about the wrong teenage Asian-American girl and tells everyone "I used to give her baths."
- On General Hospital, after Mac was kidnapped and replaced by a double, he fed the double incorrect information about his personal life, resulting in him treating his fiancée like dirt and basically sexually harassing his co-worker whom he believed was interested in him, but wasn't.
- The Thirteenth Doctors run on Doctor Who contains a running gag in which a character will mistake companion Graham, an older white man, for the group leader or even the Doctor themself (now a youngish woman). When former companion Captain Jack Harkness is the one doing the mistaking, this trope comes into play, and he plants one on a baffled Graham.
- Malcolm in the Middle features an episode where Hal, wearing nothing but a tiny swimsuit inside of a department store, spanks a customer's butt mistaking her for Lois, which results in him getting locked out of the changing room and almost having to register as a sex offender.
- In Twelfth Night, Olivia meets Sebastian and mistakes him for his sister Viola's male alter-ego Cesario, with whom she has fallen in love. Sebastian's reaction is to bewilderedly, but quite happily, go along with the romantic advances of this unknown lady and agree to be "ruled" by her.
- A rare example of a girl doing it to a man - Toakaka from BlazBlue has a bizarre obsession with female characters' breasts. In Continuum Shift, she runs into the clinic run by resident Litchi Faye-Ling, and proceeds to grab Bang Shishigami's chest by accident. Tao, being an idiot, does not realize this for a little while.
- There's a Running Gag in Sonic the Hedgehog of Amy glomping a hedgehog thinking it's Sonic, only to find she's mistaken. In the comics continuity, partway through the events of Sonic the Hedgehog/Mega Man: Worlds Collide, Sonic teases Amy by lampshading this:
Sonic: I'm taking Amy to track down Shadow. She's got a knack for finding hedgehogs - when she thinks they're me.
Amy: Aren't you ever going to let that go? I couldn't tell that wasn't you!
Sonic: The black with red stripes didn't give it away?
Amy: The sun was in my eyes!
- In Minato's sequel in Our Two Bedroom Story, the protagonist mistakes Minato's younger brother Wataru, who she has never met, with Minato when she comes home from work and sees him out on the veranda. Since his back is to her, she doesn't realize her mistake until she's already hugging him, and things only get more awkward from there.
- In one of the Summer Moments comics of El Goonish Shive, Sarah is transformed into Grace as part of a plan to prank Grace's boyfriend Tedd. Unfortunately, Tedd discovered Sarah as Grace a little too early, and kissed her, thinking she was the real Grace. The comic itself lacks any dialogue, but the commentary suggests that they decided to never speak of it again.
- Bob's Burgers: In the episode "Dr. Yap", Bob goes to the dentist and is picked up by his sister-in-law Gayle. Still high from the anesthetic, Bob mistakes her for his wife Linda and proceeds to grope and make out with her. Gayle ends up falling in love with him, and the rest of the episode has Bob trying to fix things.