not socially acceptable
not the done thing
to admit, often unwillingly, that something is true
concede
in sports, having won every game
to be unbeaten
to make a movement whose purpose is to deceive an opponent
to fake
to win a competition, argument, election, etc.
come out on top
to break the rules in a way that you consider unimportant or not harmful
bend the rules
in a competition, the person or team considered to be the weakest and the least likely to win
the underdog
to be very confident and proud
hold your head up
to fall down deliberately without another player causing you to fall, in order to try to win a penalty or a free kick unfairly
dive