This kid needs to do his "detention" with the school psychologist or
counselor. It doesn't matter whether he was trying to be "funny", get some
attention from peers, or was mirroring behavior he sees elsewhere. His
behavior was inappropriate & should be immediately addressed. If this is
behavior that may be "going around" on the football team, enlist his coach
to do a training module with the counselor too. No responsible school
system would let this go with a simple detention.