There is an interesting and often told origin for the word "tip" as a
gratuity to a waiter, or server as we call them now. But, alas, the story
simply isn't true.
While there were boxes in English inns and pubs that were used
to hold coins to "tip" the waiters, there is no evidence that these boxes
ever had the words "To Insure Promptness" written on them. The English
would have bristled over such obvious extortion.
Rather, the word comes from the 16th century verb "tip," which meant
"to give unexpectedly." The English word was derived from the German word
tippen, which means "to tap."
The expression "hot tip," as in a sure winner in a horse race, also
comes from the act of tapping. In the old days, during card games, gamblers
would have an accomplice in the room. This accomplice would signal the
player regarding the contents of an opponent's hand by "tipping the wink"
- that is, by tapping out a code with his eyelid.