It's when you grunt out the fattest log ever known to man right after you scream in terror and pain.
Person 1: Bro what are you doing
Person 2: AHHGHGGGGAGAGGHHGGHHHHH
Person 1: Bro stop it
Person 2: AAGAGGHHGGHHHHHGGGHHHH
Person 1: Holy shit that's a fat log
Person 2: *BAM*
Person 1: Damn bro you okay? Did you just grunt a stoogie?
When you go boogie boarding with your student.
Hey! Want to stoogie my boogie today?
A person that is generally dumb.
He has been a stoogy since the day he was born.