Dragon Pox and other afflictions
As a joke on a player of mine who felt the need to seduce everything with breasts in my campaign, simply because he could out skill every NPC, I came up with the Dragon Pox. Fine sized, non-sentient dragonlike creatures that infest the pubic area and occasionally fire a five foot gout of fire/acid/cold/electricity from the genital region. This is very difficult to deal with in polite company and makes armor maintenance a real pain.
Tell me your best ideas for D&D afflictions, mental or physical.