This app was mentioned in 2 comments, with an average of 1.00 upvote
Get him this, no special occasion needed https://play.google.com/store/apps/details?id=de.stefanpledl.drummersmetronome&hl=en
I use this one. https://play.google.com/store/apps/details?id=de.stefanpledl.drummersmetronome