Cereal First

Bf: Hey, what ya doing?

Gf: Just lying in bed.

Bf: Just lying in bed?

Gf: And eating cereal.

Bf: Ha, nice, what would you do if I was in bed next to you...?

Gf: Eat my cereal.

Bf: I mean if the cereal wasn't there.

Gf: I'd get out of bed and get more cereal.

Explanation

Explain Bear

Listen up, chucklehead! The boyfriend is trying to get all flirty, but the girlfriend is only thinking about one thing: cereal! Even if he's right there and the cereal's gone, she's just gonna grab another bowl. She is committed to that breakfast, and you're committed to being a doofus.