munki

I would tell them upfront, but make it somewhat lighthearted, jokish even...

Tell your waiter/waitress or slip it in as your ordering that you won tonight's dinner from an auction. Takes the coupon pressure off of you... and you can proactively be personable with your service people which leads to better service 10x over what promise of high or low tipping would anways...

This just comes from many people I've known working food/drink service over the years, collectively through stories, telling me that quality of service is always high unless somebody's an asshole, and the people that go out of their way to be extra nice... even little as learning their name... they go above and beyond for.

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