Simply ask "Cash or bitcoin" to raise awareness, particularly if you're a regular.
Ask your server if they would like their tip (maybe double it!) in bitcoin and have them download a simple custodial wallet like Wallet of Satoshi to get started; non-custodial can wait.
If you are speaking to the manager, don't necessarily try to Orange Pill them on day 1. Talk about bringing in more customers with very little effort.
Payment Providers
There are a number of merchant solutions to help vendors take payment in bitcoin and optionally convert to local fiat: