Quick question for people who know something about the anatomy of upper leg/thighs.

TW: mentions of cutting on thighs

There was a tiktok vid where a girl (in animation, not a real person) was cutting on her thigh (in picture it's highlighted where she's doing it.)

And someone commented "I do it on exact same place". Then someone replied "please don't do it on your thigh, you can cut something very important and turn into a vegetable for the rest of your life." Does anyone know what is that "something very important"? I assumed it would be a vein but that wouldn't really make sense? Or is it actually not true?

I really need to know.