I don't remember the exact site, but one guy came out with a bitcoin tip paper wallet for restaurants.
You leave the paper wallet, if they don't transfer in 30 days it reverts back to your wallet.
If anyone wonders a proper tip is 15% to 20% of the bill here in the US, we aren't paid a living wage.
I'm going to see if I can find the site and I will do an edit...
Edit:
That was an easy search, here is the site:
https://www.bctip.org/