Staying hygienic
Whether you have kids of your own, or you remember once being a kid, we’ve all borne witness to the old “smell my finger” trick. It’s important to carefully consider the person offering you their finger, what they’re likely to have done with it, and how sensitive your sense of smell is.
Usually, though you are dealing with actual children and not grown-ups. Why this guy needs his mate to smell his hand we will never know, but I’m willing to bet that it won’t be fragrant strawberries that it reminds him of. On these occasions, it’s best not to follow instructions. Maybe he should suggest a trip to the restrooms instead.