1. To utterly and completely ruin a work venture, akin to "a royal fuck up".
2. The act of rendering something useless
3. To waste time. Usually connected to people not working to their potential.
"Jen loves to screw the pooch. She has a world record high score in tetris on her office computer."
.... You know how (in the California highway construction) one guy actually works, while 3 guys stand around holding shovels watching him? - Those guys went to Screw the Pooch college to learn how to do that.
ex2: guy1-" I was so nervous with sheniqua last night that i screwed the pooch."
guy2- " ouch dude, ouch.
guy1-" ehhhh, it was good for me."