More seriously: surfing is, IRL, a relatively ancient practice of Polynesian cultures, and it's not hard to imagine it in the context of Warcraft. I don't believe there are any surfboard items, but there are lots of other things that we take for granted in Warcraft that aren't explicitly referenced, either.
Coming soon to a beach near you.
FAQ:
1) But-
A: Yes, this is actually a character I intend to play.
2) But-
A: Yes, he is an orc who surfs.
3) Bu-
A: Yes, he can surf better than you.