Flirting vs. Friendly

How do you let the barista at the coffee shop behind the counter know you're interested in him? I can't tell yet if he's picking up what I'm putting down. There is only so much laughing-at-his-stupid-jokes or asking-the-surface-questions or trying-to-graze-his-hand-as-he-passes-you-the-drink you can do. Especially when all those damn customers come up behind you. Umm – HELLO!!! Hating on my game. I realize I am already addicted to coffee so trying to go several more times a day is not helping…