Acronym for "the internet is serious business," seen in many popular internet jokes. Used when people get too vehement or serious about their forum posts/discussions by making passive/aggressive ad hominem attacks.
"Take a chill pill dude, anyone with half a brain can see that Emilio Bonifacio is the worst 3B in the league judging by half a dozen sabermetrics that if you'd taken 30 seconds to research you would have seen yourself. I don't need to come down to your level to make this case to you."
"Dude, TIISB. Take it easy."
"Dude, TIISB. Take it easy."
by Skoodog April 28, 2009
Get the TIISBmug.