to have something that you can use to gain an advantage (in a card game the ace is often the most valuable card and a cheater could have an ace up his or her sleeve to use against an opponent)
I have an ace up my sleeve which should help me when I meet my boss tomorrow.
History Facts
In Palestine 8–9,000 years ago, a dead relative was buried under the floor of the family's house – except the head. The flesh and brain were removed from the head and the skull used as the base for a plaster mould of the person's head, which was decorated and kept. .. More >>