If they're all into this and want to spontaneously do it for fun, then fine ... but it's really self-absorbed to plan ahead of time to turn this into an event at the reception that guests are expected to stop what they're doing and watch.
Spontaneous or not, it makes them look like they're 16.
Maybe at the rehearsal dinner or after party. Or if the bride and groom are 22. I am all about a casual wedding but drinking games take it to another level.
We call it tippy cup in these parts, and it's often a big part of our gatherings with my group of friends. I would not have been above having this at my wedding.
A side story - we were in a tippy cup tournament, and our team name was "Just the Tip". We dominated the competition. Just to see how it felt.
I have the same reaction as the OP. Not appropriate for a wedding....there are a ton of other fun things to do that dont involve celebrating with a drinking game! At the rehearsal or other events, fine, but reception!? I would judge, big time!