The Vole Theory is a commonly used term to describe having sex with someone small enough so that you only have to use one hand. This leaves the other hand free to do more important things, eg. Playing Playstation or using your TV remote.
The theory derives from the similarities of the consenting small person to a rodent creature such as a vole.
The Vole Theory can be used in phrases such as:
"I would vole that"
"I'd like to volulate her"