pastie

/paystee/ , n. An adhesive-backed label designed to be attached to a key on
a keyboard to indicate some non-standard character which can be accessed
through that key. Pasties are likely to be used in APL environments, where
almost every key is associated with a special character. A pastie on the R
key, for example, might remind the user that it is used to generate the
character. The term properly refers to nipple-concealing devices formerly
worn by strippers in concession to indecent-exposure laws; compare tits on a
keyboard.

