look what the cat dragged in 

Cats are known for bringing dead mice/rats/birds and other vermin they may have found or killed in to their owner's home.

Upon meeting someone who is disliked, by using this phrase you imply that they are the vermin mentioned above.

(Upon meeting an ex-boyfriend at a party)
"Well well! Look what the cat dragged in!"

look what the cat dragged in by Alpha_nine April 1, 2008

look what the cat dragged in 

An implication that someone is looking haggard, disheveled, and weather beaten...in very bad shape.

"Honey, don't I look fabulous in this new dress?"
"Look what the cat dragged in."

look what the cat dragged in by Nick D March 10, 2005

look what the cat dragged in 

Describing someone or something who looks like a dead rat on your porch.

I was looking at Peewee's girlfriend and couldn't stop thinking, "Oh look what the cat dragged in!!"

look what the cat dragged in by razzle dazzle 69 November 30, 2013

Look what the cat dragged in!

when some ones shows up unexpectedly

Look what the cat dragged in! (Look who is here)

Look what the cat dragged in! by Fernanda September 3, 2005