colloquialism - a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech

bread and butter, keep, livelihood, sustenance, living, support - the financial means whereby one lives; "each child was expected to pay for their keep"; "he applied to the state for support"; "he could no longer earn his own livelihood"

coupon, voucher - a negotiable certificate that can be detached and redeemed as needed