"Pounded like a rented gerbil" is a phrase used to describe disastrous events- usually painful financial setbacks.
As you can imagine, rented gerbils would be the unfortunate recipients of an especially rough and vigorous pounding experience, when compared with the more tender romantic encounters of privately owned gerbils. After all, you'll be returning the poor rodent right back to the rental office tomorrow, so why bother taking good care of it?
How'd it go for me at the blackjack tables last night? I got pounded like a rented gerbil, that's how! I dropped almost two grand! Fuck... that'll teach me to gamble with money I can't afford to lose.
Originally Kevin the gerbil was (ITV's) Roland rats' best friend. These days it can be applied to anyone called Kevin. Although this conjures up the idea of a man called Kevin inserting a small rodent into his anal passage this is not entirely correct. Kevin the gerbil's are fun, friendly, and a bit of a jack the lad, they are usually the life and soul of the party
when someone lets a particularly noxious fart, usually in a confined area like the cab of a fire truck, so bad in fact, that it smells as if the gerbils from Richard Gere's ass were performing a trapeze act while suspended from the air conditioning vents.
firefighter 1: dude! you stink!
firefighter 2: oh i know, i'm terrible today!
firefighter 3: JEE-sus! smells like a fuckin gerbil circus in here!