L.l.a.f.
L. l. a. f. is when you're laughing so hard it looks like you're trying to explode. It happens when you're drunk, high, or just plain dumb.
I laughed like a fuck when my friend told me my dog tried to talk to the mailman.
At the dinner table, I laughed so hard I dropped my fork.
My brother laughed like a fuck when I told him I got a D on my math test.