More commonly referred to as a common squirrel.
1) The ugly tree rat immediately grabbed the nut and ran.
2) The tree rats were all around the bird feeder.
1. To leave the presence of others that are annoying in a decisive manner.
2. Having sex with someone named Alan.
3. To deal unto others violence in the most unpleasant manner imaginable.
1. Jon picks up his things and leaves angry.
Jill- "What is his problem?"
Bill- "He's just doing an Alan."
2. Bob- "So, if you're not busy later, maybe we can hook up?"
Jane- "Sorry, I'll be doing an Alan."
3. "Oh, My God! What is that man doing?"
"Just Run! He's doing an Alan."