Gently if it seemed like he was really bothered by it, not-so-gently if it seemed more like him being a drama queen.

Oh, she will relentlessly tease him. This whole joke probably developed when she mentioned she wanted a tattoo in high school. Maybe he was along the lines of "Yeah I'm tough enough to get one I'll so get one," and when she did "I... didn't think you really meant that..." ?

I don't know, I'm admittedly canonblind, haha