I think the general idea is that you should contribute twice the drinks you consume because not everyone will always play by the rules and this will not necessa

I think the general idea is that you should contribute twice the drinks you consume because not everyone will always play by the rules and this will not necessarily be a bad apple. I can easily imagine myself drinking from that fridge for days, then one day bring back three 6-packs into the fridge because I saw an offer and carrying them to work would not be an issue because "I'll go with my car next week". Something alike :)