The word 'punch" has several meanings. It means to hit someone with a closed fist; it means to place a circular hole in an item. It also means a liquid consisting of fruit juices. In the phrase "get some punch" the punch refers to the mixture of fruit juices. Punch is served in a punch bowl and those who wish to have some will "get some punch."
Example: Maya, you should get some punch. It tastes delicious. (I hope this helps!) :-)