He didn't understand the gravity of the situation.
Curses, foiled again!
Because he didn't study.
An offer you can't understand.
Ten. (Shame this one doesn't work too well for reddit - the funniest part of this joke is the third punchline enjoying people struggle to understand what the hell you're talking about.)
It was a high school.
Gravity. It's always bringing me down.
I don't think you understand the gravity of the situation.