I have a couple of Pet Peeves. Here we go:
#1- "itch". The word "itch" is a noun, not a verb! You don't "itch" and itch, you scratch it! It drives me crazy to hear someone say "I have an itch." and then someone else saying "well, then itch it." Say SCRATCH it!
#2- When people put empty bottles or containers into the fridge. Throw them away!
#3- When people throw away things that can be recycled. C'mon, people! Recycle! Help the earth!
#4- When the person you are talking to on the phone talks to someone else on their end. It's ok if they say "just a second" or something, but just to start talking to someone else is annoying!