Originated by the Penny Arcade strip "Prefanity", "Strawberry Smurf" is some perverse term involving arbitrary sexual acts, necrophilia, and gnomes. This can include any form of Gnome, whether it be from Warcraft, D&D, or just an exceptionally short person in real life.
Last night I decided to roll an alt on Moon Guard and check out what was going on in Goldshire. Some Gnome chick asked me to give her a Strawberry Smurf. I logged immediately.