Rattlemouse 

A troublesome thing to accomplish
Something hard or a pain to do

Man, building that deck was quite the rattlemouse!

Rattlemouse by Brandoniron February 26, 2013

RattyMouse 

1. In some South American countries where small rodens are common, people struggle to differenciate between a mouse and a rat, so they use the name "RattyMouse" to describe both.
2. The description of a loveable partner or friend that has rodent like feature.

Jose: Damn man, who ate the rest of my chicken I saved last night, I was going to have it for breakfast?
Enrique: It wasn't me amigo, I saw a "RattyMouse" eating it last night, but I was too drunk on tequilla to do anything.
Jose: You drunk fool! Now I will be hungry all day because I didn't get my breakfast. It's your fault.
Enrique: I hate you!

RattyMouse by Paul Fleming July 14, 2006