Drinking Enemy
A friend or an acquaintance, that when booze is involved, proceeds to become your drinking enemy. This can be viewed in a positive light but extreme caution needs to be in place as the sole motivating factor for a Drinking Enemy is to take you down with them.
Greg, you are a great guy but you have made way too many drinking enemies in the past. Or,
Adam, you may be my drinking enemy, but will you be my Best Man?
Adam, you may be my drinking enemy, but will you be my Best Man?