Like, the whole point of the joke is that he walks into a *coffee* bar and treats it like one that serves alcohol. That's obvious in the second panel.
Also, why is she polishing a beer-style mug in a coffee shop that doesn't use them? That doesn't make sense, but if you'd used it as part of a punchline that was an actual punchline, it could have seemed very clever. Something like this: he orders the strongest thing they've got, and sets his head down on the bar. A panel of hissing and steam in the background suggesting she's making espresso. Then, a beer mug full of steaming black coffee is set down next to his head. "We keep the mugs around for guys like you," she says.
Try to act these stories out a little before you go to the hard work of illustrating them. Try to make someone laugh with just your script. It'll help.
So for the next little while, I might only be uploading in a bi-monthly fashion. I should the weekly schedule back on track eventually, though.