S.N.
I'm having the same problem with my 21 month old. Lately I grab any "interesting" object on my way to the changing table. I try to choose something he hasn't seen before or that I wouldn't typically give him (my watch, an envelope, a remote, a small travel-size bottle of something from the bathroom, etc.) Toys worked for awhile, but now he is so interested in holding something "new" that he is distracted just long enough to change him. (although I still have to be pretty speedy!) Good luck!