This is a Dutch blindfold game called Koekhappen. The players have to eat the biscuits on a string using only their mouths. If you’re going to try this, have plenty of tea towels ready so you can blindfold them and maybe also tie their hands behind their backs. If you are tying hands together for blindfold games, make it clear from the context that they are not being bound and blindfolded, it’s just a party game. The best way is to ensure they can untie their hands themselves.