What made us laugh?

What made us laugh, that time,
Do you remember?
How we howled and rolled on our backs,
You clutching your waist and me weeping,
It took us like a fever, or waves,
Another surge rising with each moment,
Wild and loose and loud.

But what made us laugh, that time?
I can't remember how we began,
Only the little lines in the corners of your eyes,
And the fullness of your smile,
And how, after, we lay there for an hour catching our breath,
Exhausted by joyfulness.