Weird way to masturbate...

So I'm not sure if this is normal but I'll start from the top. When I was in the fifth grade I discovered that crossing my legs and kind of squeezing them together felt really really good. At the time I wasn't sure what it was but now i do it as a form of masturbation. Again, not sure why or how it occurred to me to do start doing that...but I'm wondering if anyone else has done or does this??