"Butter on my corn till I pop" is a way of saying someone is indulging in something until they reach their limit, much like slathering butter on corn on the cob until it's swimming in it. Imagine a piece of corn so enthusiastic about getting dressed up in butter that it doesn't know when to say "enough!" and keeps going until—pop!—it metaphorically transforms into a popcorn kernel bursting with too much excitement.
Alternate:
Edge until climax
“Jeeze I’m about to lose myself playing Plants Versus Zombies Garden Warfare 2 tonight, just butter on my corn till I pop!
Alternate:
Person 1: “Richie’s mom is such a milf.”
Person 2: “Yeah, she can butter on my corn till I pop!”