According to the search results, "whippets" can refer to different things:

• An area of skin located on the upper, inner thigh that has become hairless through constant friction of walking and other physical activity.
• A type of dog produced from a cross between a greyhound and a terrier, bred for racing.
• A small container of nitrous oxide gas (N2O) used officially in making whipped cream, but more often used recreationally for its euphoric effects.

Therefore, the term "whippet" in the Urban Dictionary can refer to any of these three things depending on the context.