When a trainer brings a "twinkie" into the free weight room. The constant giggling really annoys me.
Last week, a trainer brought in a "twinkie" while I was benching. She nearly had a heart attack when she thought he was going to have her do "that" (btw, as of last week I only had 20lbs on the bar - not much). Then when I did my deadlifts, she had this look on her face like "why is she is doing that?" "That's so manly." So, I let the plates hit the floor so she would get the point. I haven't seen her in the weight room since.