Whenever I have a vaccine or get a blood test, when the needle goes in and I have that sharp pinching pain, I start to laugh really super hard.
I just can't control it, just something about that pain or the idea of having a needle sticking into me is hilarious and I start to laugh almost hysterically.
When they put a small mount of local anaesthetic on a cotton ball and tape it to the entry point, not being able to feel that part of my body makes me have spasms in the direction of my arm. Sometimes these spasms make me laugh.
It's interesting because when I had an IV drip from being in hospital from appendicitis I didn't laughter then when it went into my wrist. Maybe it's something to do with the inside of my elbow or my shoulder.