Ok surprised no one knows this however you use a moist paper towel to keep things like cigars and additive free cigarettes ( Like Nat Sherman, or, Natural American Spirit) and you can also use it and a pair of ziplock bags to restore moisture to stale tobacco, or cigarettes or cigars or, filtered cigars, etc
However you normally would NOT use them on cheap cigars and cigarellos, because there cheap among other reasons
Of course if your kid found out about the napkin trick or the use of humidors, as they are inexperienced with tobacco, then it is possible they are trying to keep them fresh, maybe they smoke one or two per day? Idk - when asking, don't act mad, just ask why he has damp
napkins in his cigar packs - Do what you want obviously, however a simple even tempered question, at least to start, will get the best quage of their response, and, maybe even the truth. In any case, if it's not true, you figure it out afterwards. Just my advice
And tobacco is bad, however cigarettes are worse and more addictive than cigars, so wouldn't yell to much if they close to legal age especially, it seems to have opposite effect. Find out about those napkins, which you didn't tell us much about
Ugh giving out parenting advice!