Foop is a time when you really feel like you hafta fart, and you think, what the heck? Why not, right? So then you fart and later you check your under pants and there is a "foop" right there.
Fooping can also happen in showers, pools, and many other locations you may feel alone in, but your not, FOOP WILL BE WITH YOU!!!!!!!!
"When I was using the bathroom, I found a little foop in my pants...."
The officer was striped of his badge when he was caught f.o.o.p.ing paper work.