an itchy palm
What one is said to have when they need or want a tip or bribe. A: "I can't believe that guy at the desk actually answered all of your questions!" B: "Ah, he just had an itchy palm—a little money made him more inclined to talk."
*itchy palmand *itching palm
Fig. [of a hand] in need of a tip. (As if placing money in the palm would stop the itching. *Typically: get ~; have ~; give someone ~.) All the waiters at that restaurant have itchy palms. The cabdriver was troubled by an itching palm. Since he refused to carry my bags, I gave him nothing. Whenever he sees expensive luggage, the hotel doorman gets an itching palm.
Also, itching palm. A desire for money, greed; also, wanting a bribe. For example, The porter has an itchy palm; he wants a big tip, or The mayor was known for his itchy palm. This expression alludes to placing money in the palm of the hand. [Late 1500s]