Present tense of bested. "Besting" someone is the continuous aspect of beating someone at their own game. Getting the better of your opponent or adversary.
I love besting my frienemy by sleeping with her boyfriend. I know it's naughty, but it makes me feel all warm and tingly inside.
Besting - adj - amazing, or the best ever
- vb - to do something amazing or the best ever
ADJ: Oh my God Amber, this cake is so fucking besting!
VB: Remember when Lindsay and Jake were besting it up when they decided to become a couple.