Try NOT getting the can on United...
Me: 'Can I just have a glass, no can?'
FA: 'Just take the can, maybe you'll want it'
Me: 'But I know I won't drink it all, I only want a bit'
FA: 'It's easier this way'
20 minutes later I drop a nearly full can into her trash bag (warning her first)....hey, I tried to avoid this.