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
2. Anal sexual stimulation.
a. Applying a tape casing to an actual gerbil to prevent its dissolution (or unsightly claw/bite marks) in the rectum.
b. Any sort of rectal gratification.