Lifty and Shifty were planning to steal things from your home. They took advantage of the fact that you were sleeping and entered through the window, being very clever. When they were about to leave, they both tripped and broke a vase, causing you to wake up.

Lifty:- "Oh, well done, fool!!" -

Shifty:- "What are you talking about?! You tripped first!!"-

They didn't even look like thieves anymore. Now they just looked like two little twins arguing.