shot buddies
The person with whom you are taking a shot, of alcohol, with.
Danny and Jessica prepped their shots with Jack Daniels and imbibed them. Thus the two became shot buddies.
Shot Buddies
They are probably one of your best friends and someone you can tell anything to and trust with your life. They are the person that would do anything for you and always keeps you strong and is kinda like your battle buddy (meaning whatever you do/go that's what they're gonna do also). Your 'Shot Buddy' ultimately is most of all the person who won't let you drink alone (because that's just sad) and will always be there to look at you and say "If you take it I will".
Becky saw Zack taking shots by himself at a party so she went and took them with him, they became shot buddies and now bestfriends.