I feel like this is one of those things that 100% varies based on the inflatable
some inflatable critters have functioning mouths, some have decals; some don't think too much about what's inside them, and some are very strict about how many air chambers they have. so I imagine there are some inflatable characters that could drink coffee fairly normally; some where they could only pour it into a nozzle but still like, be affected by it (and maybe even digest? it); and some where it'd go into them and just slosh around in their tummy area until emptied out one way or another!
that's how I see it at least, and I'm sure there's plenty other inflatable characters who have their own ways of doing it 83
