During a boxing match a spectator is congratulating a boxer for winning the previous match saying this sentence:
What is the meaning of おめでとさん? He his clearly congratulating the guy, so I think it must come from おめでとう, but why the omission of the う and the addition of さん? I don't think it could really be the guy's name.
Here you can see the whole page where it is taken from. Thank you for your help!