nip on

nip on

1. To give (someone or something) little bites. Their dog kept nipping on my heels whenever I walked through the house. I felt some nipping on my toes during the night, and I absolutely freaked out
2. To take small, frequent sips of some drink, especially alcohol. I caught my grandma nipping on a flask, which she tried to pretend had medicine inside of it. He nipped at a bottle of whiskey to help keep warm as he trudged through the snow.
See also: nip, on
Farlex Dictionary of Idioms.

nip on

v.
1. To grab and pinch or bite: The fish nipped on the wader's feet.
2. To sip some drink, often alcoholic, in small amounts: The guests nipped on their eggnog all night long. I nipped on my soda while waiting for my date to show up.
See also: nip, on
The American Heritage® Dictionary of Phrasal Verbs.
See also:
  • nip at
  • nipping
  • nip on (someone's or something's) toes
  • nip on (someone's or something's) heels
  • hard on (one's)/the heels
  • hard on your heels
  • hard/hot on somebody's heels
  • be toes up
  • toes up
  • on the heels of (someone or something)