Snipe had been tense lately (it usually happens around this time, when his students start actually using real firearms for practice) so no one really gives it much thought when Izuku starts spending less of his cuddle time with the others in favor of following around Snipe. He hangs off his back, walks with their arms entwined, sits against his side, wears his hat, decorates his mask. The only place he reluctantly doesn't follow Snipe is into the shooting range, at Snipe's plea to keep his mind at ease and stay away from loaded guns after the first disastrous time where he almost gave Snipe a heart attack.
Snipe had been working his third years through the first practice with real firearms when Izuku had popped up on his shoulders with Snipe's hat on his head. Snipe had barely noticed the now familiar weight, but it caught his students off guard. One of the boys had screamed and startled one of the ones shooting, who whipped around to see what had happened. His arms followed his head, his finger twitched, and now Snipe's hat has two holes in it and more grey hairs than his mother.
Needless to say, Izuku was not allowed into the range again, and both the boys got detention for reckless handling of a weapon and causing a disturbance.