E.I.F.F.
E. I. F. F. stands for 'Easily Identifiable Fat Friend.' They’re the guy who shows up to every party and makes everyone else look good by comparison.
'You brought the E. I. F. F. to the bar? That’s how you ruin a good night.'
'I’m not fat. I’m just a walking E. I. F. F. endorsement.'
'He’s the E. I. F. F. of the group. We all know it.'