The person who goes with you to the bathroom when you're drunk. During this time they are also your best friend and you usually bond over the most insignificant things.
Amy and Danielle go to the bathroom at a club.
amy- "oh my god danielle youre my BEST friend i love you so much thanks for coming in here with me"
danielle- "OMG i love you too potty buddy!!! we're gonna be best friends forever