This is a common problem in the bartending world. Most bartenders don't realize that you don't want to muddle mint while making a mojito, or any other cocktail that requires mint leaves for that matter. Mint leaves only need a light press to release the oils to flavor the drink. When you muddle the mint it brings out a bitter taste that overpowers the natural mint flavor. So, the next time you make a mojito - go easy on the mint!
The simplest and generally the most rewarding way is to be so nice it is almost sickening. When you are all smiles and laughing but polite and guiding the customer has no real choice but to go with the flow. The best "cut offs" and walk outs start with just being honest and leaving no room for negotiation. Always know someone's name before you push them on the exit path. It gives you more credit with them and their friends and establishes you are not some jerk ending the fun you are just the guy or gal who is doing there job and being responsible.
For example: "Cameron buddy i think your time at our fine establishment is coming to an end(place laugh here)you have a ride home or should I call your parole officer....again?(hit up another laugh and grin and wait for the reply).