Does karma really work?

I’m not religious or anything, but I do believe in karma very much..its not even because I want to, but because it works for me every time!...I have a bunch of guy friends, and they like to pick on the little one (which is 99% me) all the time. So every time they try do so, something bad or embarrassing happens to them within seconds of tricking me. Ex:Spilling soda on their pants, Choking on food, Stubbing their toe…things of that sort. So my question is, Does it work for any of you guys like it works for me?..Or is it just their bad luck and timing?