When said person does something that seems out of character, in a random, and expected fashion, and to the public eye there is no obvious motive to said actions, so it seems like something out of the blue.
“Hey, did you see Kandi Burs parodied the Kylie Jenner cameo in the WAP music video?”
*laughs
“Omg Kandi just be doing stuff”
When a girl is trying to take a shit after eating thanksgiving and you stick your dick into her, pushing it back in
“Hey Chris, my girl was wanting to be freaky last night after thanksgiving, so we decided to go and re-stuff the turkey
An item of interest i.e.(boat, pet, house, girlfriend) that requires many ancillary purchases
My free puppy turned out to be a stuff bomb. We have spent thousands on toys, special food, housing, and carriers after only 2 months.
What they teach you in the navy to be useful to your comrades... And prison. It's stuff you do revolving around a boat, or a metaphoric boat. Definitely no second meaning.
A good example of it's use would be
"Hey soldier, have they taught you boatt stuff yet? You need to get that down if you're gonna survive here."
or
"Hey homie, I know you've learned boatt stuff, come show me how it's done >:)"
Sexual acts done in the bunk of a truck.
Guy 1: Hey this salesman tried to sell me a truck at a really high price.
Guy 2: Did he at least give you some bunk stuff at that price.
That special something which allows a person to perform at the highest level.
Or
The actions themselves which require that special something to perform at a desirable level.
"We've got to sign this kid to a contract, he's got the stuff."
"The artist has refined their techniques and style through their years but it is clear even from their early works that they always had the stuff."
an youtuber who has a bigger dick then you
neri-does stuff just posted an banger video