Elf: Twink
Half-Elf: Half-Twink
Dwarf: Stump
Half-Orc: No brains to beat out of you, even if I tried.
Gnome or Hafling, just fart on their head and that should be enough to insult them.
You could also ask a dwarf, gnome, or hafling, if they mated with one of the others to get the third race...