Wearing a mask for a long period of time isn't worth it. You're recycling your own moisture/ CO2 in your own body, and depending on the fit of the mask, breathing it back and forth against your face also exhausts energy. In short, unless you're super desperate, it's not fun.
I work a moderately strenuous job in a face mask. Judging by my own experience, with a mask has insignificant changes in my own ability to do the things. That being said, who wants to brace this crazy world we live in right now with covid stress and processed food that's being shown to be way bad for you stress and humans judging their own brothers as inferior stress that has everything to do with you should someone decide to ruin your day just to get seshed..... idk. It's not just the covid. Going Ebay i can isn't going to be what brings the world's back in balance overnight but at least if i don't know how to be effective at least I'm presently wise enough to stay out of the way. Who knows though, i might have enough of thew brain screaming at me for a fix one day and be selfish but it is not today.
I would pretty strongly recommend not doing this even if the subject is perfectly healthy. If you want something roughly comparable, use exercising as a comparison, but I would keep in mind that the lee is going to be inhaling/exhaling a lot, like an extended run. Maybe if you're doing really light tickling?
Choirs have been a major case for transmission because of how easy the virus is spread in closed rooms through as the singers are belting their notes without a mask. Tickling is at least 1 on 1 unlike choirs, but without a mask on it's a major risk for transmission. It's a risky activity nowadays, so I would rather use a mask with lighter tickling in a COVID world.