Principal Skidmore has Fletcher paint pictures of her in a school girl outfit in suggestive poses for a "gentlemen friend".
Another episode has Cameron mentioning to his dad about how he scratches his-[beat]-self.
In yet another episode, Fletcher paints a picture of his "freakishly large toe". It's really long, and pink. In fact, it's so glaringly obvious that it's a shock that Chyna's first thought was "finger".
In "America Needs TalANT", Olive spews out a couple of obvious Unusual Euphemisms: "Press the buzzing buzzer!" That episode was the most radar-y yet. Among other things, Cameron got essentially raped by a walrus.
In "PatANT Pending", Olive sounded like she was trying to stop getting an orgasm from the backpack Fletcher made.
And the Halloween episode and the pilot (before being edited later):
Also in "StudANT council" at the end when the girl shoots for the bunny (who is Cameron) wins and he goes home with the girl.
In an episode of season two, Cameron has an imaginary girlfriend (played by Vanessa Morgan). She lifts his leg and puts it on her lower leg for a picture (taken by Olive).
In "Bad RomANTs", Fletcher says when alone with Chyna "I don't remember the time that we were alone, just the two of us." Then later during the same episode when alone at Chyna's house Fletcher then says, "Say I have 5 chocolate covered strawberries and I feed you one. How many do I have left?" He then tries to feed Chyna but Gibson rings the doorbell. Fletcher obviously tries to make some moves on Chyna.
Angus goes over to Lexi's house to help her with her computer. But him talking about his "skills" (which Lexi confirms unknowingly) hearing Lexi talking about cheerleaders who want his number and how she "needs" him leads Cameron to believe something else is going on...
In "Modeling AssignmANT", when Olive and Fletcher are trapped behind bars at Hippo's Prison Themed Restaurant, Lexi says to Olive "it's time for the Cavity Search." It's a bit of a subversion, because Fletcher and Olive looked appalled, until she breaks out a dental mirror and checks Olive for cavities. However, it's the way Lexi says "Cavity Search" that makes it worth noting.
We get this in "ANTswers" after Olive helps Paisley with her parrots.
Paisley: Wow Olive, who would've thought that five minutes alone with you would be so amazing? (Cue Angus giggling and bashful raising his hand)
In "PhilANThropy", Cameron in return for helping Lexi, asks her for the names and numbers of the losing pagaent contestants. He then comments on them being not quite pretty enough and having low self-esteem. Meaning they either are desperate or slutty.
In "Body of EvidANTs" the "mouth" of Olive's electronic pet is located in... shall we say a rather private area and something is frequently inserted there when it needs to be fed.
Does Fletcher yelling "How am I supposed to know, I'm not a urologist!!" instead of zoologist when Chyna and Olive have to replace a duck in "Animal HusbANTry" count?
In "ConfinemANT" Lexi describes herself as "Lexi and I Know It" which is a take on the highly sexual song "Sexy and I Know It".
Heck, the show's own wiki has an entire page devoted to this phenomenon in the show.
In the third "MutANT Farm" episode when the mutants have crossed over into the main universe and Mutant Olive has sealed the rift, Zombie Angus says "The universe left it's fly unzipped." to which Fishgirl Lexi says, "In the universe's defense, so does Fletcher."
"Unforeseen circumstANTs" has Lexi tricking Olive into doing room service during their study hours. She asks Angus to pay her 10 dollars for Olive to clean his room, but when she only gets half of the amount he gives her this response: