On a tear 

On a streak or series, usually a winning streak. Will sometimes be used (semi-sarcastically) to define a losing streak.

When used for a positive streak, it's similar to "tear it up."

He won four bike races in a row--he's on a tear!

The market went up 14% in the least four weeks. The market is on a tear! (aka "The market is tearing it up!")

On a tear by Wayne the definer April 2, 2009

on a tear 

a string of behaviour that is compulsive and devient. the bahaviour is typically of an "adult" nature such as drinking, screwing, swearing.

Jill was so pissed about the flat tire that she went off on a tear. Every other word was fuck.

Brad has been on a tear of calling in sick recently. He hasn't worked a Friday in over a month.

on a tear by Cliff96 April 26, 2006

on a tear 

to have recently engaged in many sexual acts, with many different people.

Wow, Lizzie has been on a tear lately. She's banged like everyone in the sophomore Kappa Sig class!

on a tear by hahaslizzie May 27, 2005