Woof'd Up is a verb. You can use it in place of other popular terms like screwed up, messed up, f'd up, etc.
You can add I, You or They in front of it to describe who did the Woof'ing Up.
iwoofdup.com is the web site that made this term popular.
Husband: I forgot to make reservations for our anniversary!
Wife: You Woof'd Up!
I was supposed to turn in that report to my boss and forgot. I really Woof'd Up.