A delay of kickoff is a penalty in Football that is called on the kicking team during kickoffs if they fail to kick the ball before the 40 second play clock expires. During a kickoff after the ball is set, the head umpire blows their whistle to begin the play clock. If time expires and the ball has not been kicked, the kicking team will be assessed a delay of kickoff penalty. This penalty is very rare as most of the time, teams kick the ball seconds after the whistle is blown. A delay of kickoff penalty is the same as a delay of game, the kicking team is penalized 5 yards.
A team may purposely wait to kick the ball and receive a delay of kickoff, possibly to rest players, waste time, or to give the kicker more room to kick the ball, but that is unlikely as the kicker has the entire field to kick during a kickoff.