I'm very used to getting my blood drawn: It's a rather common occurence for me. However when I went for it recently, I got the nurse who isn't terribly good at it and since the other nurses were busy I had to have her. She has a rather unsteady hand and insterted the needle way too far. It hurt more than necessary. Anyway, I find most people very uncomfortable during needles so I have a list of funny things to do during a blood test.
1.) Ask if you can keep the needle to remember the day by.
2.) After the needle is finished, smile at the nurse and go "Now it's your turn!"
3.) If someone is getting their blood drawn/a shot nearby, stare at them with a huge grin. If they look at you, continue and don't lose eye contact.
4.) If there is a box filled with tubes with different colour caps, tell the nurse which ones you want.
5.) Halfway through, gasp and go "Don't take all my blood!"
The list is rather short: I've never really thought about funny things to do during a blood draw before, mostly just of what to do at hospital and such.