Tags is a purple monster from The Mo Show, and is Mo's older cousin. He had his own show called Tags Time before The Mo Show.
Before the Mo show he was red that he looked very similar to Elmo, and then in a video called "Purple", he made his last appearance in red and changed purple. The most recent puppet made it's first appearance in Season 4 Episode 9 of The Mo Show.
Tags is good friends with Frank and Mo.
Tags in "Tags Time"
He is the local cool guy and rapper of the main Mo Show characters and is presumably a parody to Whiz Khalifa or Snoop Dogg the main rappers of California.
The original red Tags Monster with Telly Monster (left)