Synonymous with "pussy". Someone who gets scared and pussies out of anything.
"Jim was going to make a Facebook, but he nipped out."
Person 1: "Skull this beer."
Person 2: "No, I have to go to work."
Person 1: "Shut up you nip."
Person 2: "Awwww..."
Person 1: "NIP NIP NIP NIP NIP NIPPERNIPEERPINPINPPERNIPNIPNNIPNIPNIP"