I think their armour is waterproof.
When I read the Strobist blog post today I realised I'd not done any water drop shots for ages. The randomness is fun, and 240 decisive moments later, one of them turned out decently!
Strobist info: SB-800 on 1/64 power into white shoot through umbrella to camera right. Triggered by gadget infinity remotes (until my Skyports arrive!).