I have 2:
1) March of Dimes - that "baby won't stop crying" commercial. They have babies crying in the background almost the entire time - what is more annoying than a baby crying. And why is it on so often. Shouldn't they spend less money on advertising and more on helping babies?
2) Milk for Health - "milk times three is good for me" (or something to that effect). At the end they have this little boy trying to say it and he can't. That kid annoys the heck out of me.
I'm not fond of kids - can you tell? LOL