Plan ahead!! 🙂 Ask either your Bishop or a member of the Bishopric, or a male teacher in Primary to either wear a tie they don’t care about and you can cut up, or bring an old tie they can put on when the kids are not looking.
Tell the kids that you want to show the Bishop (or who ever you ask to help) how great they are singing, ask that person(s) to come up to the front, after they sing you tell the kids you are going to cut his tie as they sing if they do a really, really good job on the song.  Then get a really big pair of scissors, you are gonna have FUN WITH THIS!
You can ask the bishop if he thinks it was good enough? He can play along and say, no, not really, let’s hear it again. Or he can say, “Well it was okay, maybe good enough for one little snip!” and then go ahead and cut one inch off the bottom of his tie. The kids will absolutely LOVE this. And a great way to ge the Bishop involved.