L.l.a.f.
L. l. a. f. is when you're laughing so hard it looks like you're trying to laugh yourself to death. Usually happens when you're drunk, high, or just plain stupid.
I laughed like a fuck when my friend told me my dog tried to wear my hat.
At the concert, I laughed so hard I fell over.
My brother laughed like a fuck when I told him my math teacher got stuck in a desk.