Photo: Bob Horowitz

Yes, kids, the annual tradition of Valentine's Day pillow-fighting at Justin Herman Plaza and clogging all the storm drains in a 500-yard radius with feathers is happening, once again, tonight at 6 p.m. It's yet another reason S.F. is known for its whimsy, and flash mobs. Sigh.

We'll try not to be cynical spoilsports about this if you're new to town or if this sounds like an absolute blast. It's fun! It sure is. Anyway, a few recommendations: 1) Bring a mask or wrap a bandana around your face, because a lot of feathers and other debris will be filling the air and you don't need to be breathing that. 2) Bring your own pillow... they will not be provided. 3) Bring a non-feather pillow... this way, your pillow will not disintegrate within minutes and you will have more fun. 4) Let's keep this light and fun, huh?

See some past photos and videos if you need to get an idea.

[SF Fun Cheap]