Cartman gives his first kiss to Butters, because he's sure he won't be rejected. Butters is as gay as they come: flamboyant, effeminate, and born to take it where the sun don't shine. Instead, his lips remain frozen and unmoving.
"What the fuck Butters? Haven't you ever kissed someone before? Goddamn."
Then Cartman realizes, of course not, because Butters is genuinely as naive as he appears. Cartman likes that about Butters.
"It sure is nice that you like me an' all. But Eric, I don't like boys."
Cartman's jaw drops.
"I won't tell nobody," Butters offers, like it's any consolation.