Well the Marines had a booth at a water park and were giving away t-shirts if you did 25 chin-ups. I ended up doing 50, 25 at a time with a few minutes rest in between (both of my kids wanted a t-shirt). So in one set, probably around 35-40
I don't normally do chin ups with my workout, but after reading this question I was curious to see how many I could do. I did 5 - actually more than I thought I could. Looks like I need to do some more lat pull downs.