fist bump
noun /ˈfɪst bʌmp/
  /ˈfɪst bʌmp/
 (informal)- a way of saying ‘hello’ or of showing support or agreement, in which two people raise one fist (= a hand when it is tightly closed) each and lightly hit them together击拳,碰拳(表示打招呼、支持或赞同) - do/give a fist bump击拳致意 
 
- do/give a fist bump