A fake spike is a trick play in American football. When the clock is running low, it is not uncommon for a quarterback to spike the ball to stop the clock, either to set up for the next play or bring on the special teams. Here though, the objective is to trick the defense into believing that no downfield play will be run.
A famous example occurred in 1994 with the Clock Play, when Dan Marino's Dolphins were playing the Jets. From the account of Pat Kirwan, former Jets defensive coach and executive,
With little time left, Marino had driven the Dolphins near our goal line and lined up as if he were going to spike the ball to stop the clock. But instead, he faked the spike, and as our defense let up for a split second, Marino threw the winning touchdown.
Peyton Manning was also a frequent user of the fake spike, and "sold it" so well in a 2001 game against New Orleans that the referee Jeff Triplette blew the whistle to stop the play, costing the Colts a probable touchdown.