To me, there's 3 that comes to my mind:

Ping Pong
Equestrian
Curling

I'm not sure when Ping Pong was made an official olympic sport, but I always found it odd to see it as an olympic sport. I mean, you can make a case that table hockey should be a winter olympic sport if that's the case. Equestrian only shows what horses can do, and I've always questioned that as an olympic sport.

As for curling, it's pretty much the world's greatest janitors. I mean I try to like it...but can never really grasp why some people like it so much.

As for archery and air rifles, I never really questioned them as olympic sports...mainly because it's so tough to actually aim and takes a great deal of concentration.

Oh yeah, and rythmic gymnastics...it's more like a drama rehearsal than an olympic sport. That's questionable too...but eh.