In the pilot episode, "Dead Man's Drop", Kick ends up naked.
As part of an unusual plan Gunther shows up at the Buttowskis' doorstep dressed in drag, when Brad opens the door this is his reaction:
Brad: (sighs wearily) Not this again, Gunther.
In "Knocked Out", Gunther's smelling hands addiction can be interpreted as a G-Rated Drug.
In "Not Without My Cereal", Kick accidentally bumps into Honey's rear in the store, causing the bag of bread buns she was holding to fly upwards and then land in the arms of a nearby shopper, making it look like he stole them, Honey's response?
Honey: I'll thank you to kindly keep your hands off my buns!
"In Battle For The 'Snax", when Kick decides Gunther's family's restaurant needs a theme, there's a quick scene of Gunther entertaining the thought of boogying around in an outfit reminiscent of a Hooters waitress. And to top it off, the shirt has two blue-footed boobies on it.
Let's not forget the "goodbye" part, when Gunther gives Kick a photo of him in a sensual pose and giving a lustful stare, along with a message written "To Kick, XoXo Gunther".
The Fake-Out Make-Out scene in "Box Office Blitz" reveals that Kendall keeps a rape whistle on her person.
From "The Treasure of Dead Man Dave":
Gunther: So how did you escape from [inside] the Giant Rat queen?
In "A Fist Full of Ice Cream", Kick and Gunther are riding down a stream on an ice cream truck. Gunther exclaims "Dam!" referring to a wall that keeps back water, which Kick scolds him for, but Gunther tells him that they're about to hit the city's dam. They both then yell out "DAAAAAAAAAAAAAAAAAAAAAAAAAAM!"
She also noticeably checks out his backside as the guy walks by.
The very premise of the episode "Sold!". In a nutshell, Kick legally sells himself to Jackie under the obligation to do whatever she wants for a day.
In "Faceplant", after Kick escapes the giant screws the host jokes, "This kid's not screwing around!"
In "Hand in Hand" when Brad sees Kick and Kendall (dressed as Gunther), he takes a suspicious glance at the fact that they're holding hands.
Kick: ...Don't judge us.
In "Detained", when Gunther thinks Kick forgot about telling him how cool he is, Kick presses his cheeks and then starts to talk about Gunther. His reaction? He blushes and acts like if Kick was flirting with him. Ho Yay much?
"Bwar and Peace". When Gunter is whisked off to The Old Country, his parents exchange flirty glances, run off to the bedroom, and the sound of squeaky bedsprings are heard...because they were jumping on the bed.
From "Pool Daze":
Brad: If I do what she wants, maybe she'll do what the Brad wants.