look up any word, like bukkake:
acronym that stands for "Shut the fuck up, loser."

Sometimes pronounced like "stuff-fool"
<ineedfriends0132> my life sux, y won't u guys be nice to me ur so mean plz be my friend :(
<coolguyx1035> STFUL
<ineedfriends0132> :(
* ineedfriends0132 has left the channel
by interwebmanx99 June 06, 2004
"Shut the fuck up, lamer."

pronounced stuff-full or s-t-f-u-l
next time you see someone acting lame, tell them to STFUL.
by Ananonymousmouse June 07, 2004