There are numerous ways that you can't tackle in the NFL. You can't grab by the facemask or by the collar of a players jersey.
It seems that you can however tackle a player by his manhood.
Recommended
That's what TJ McDonald did to 49ers tight end, Vernon Davis, last night.
https://www.youtube.com/watch?v=gN1IwK9Cbho
For some reason Davis has since deleted this tweet. You can't really argue with the reasoning though.
