Short for "time vacumn", because a television —and any other devise with a screen, such as computers, portable video games, cell phones, etc.— tend to suck your time away without you noticing.
"Sorry I'm late for our wedding, honey. I sat down in front of the TV and didn't see the time pass".
"But Larry ... you don't HAVE a TV!"
"Oh, yeah. I meant my digital camera. I was taking pictures of my penis to get you hot for our honeymoon, and I couldn't stop retouching myself"