For me it’s a little less haphazard, but I’m guessing this person has lived something of a life of privilege and is probably significantly younger than myself.
I had an ex who was arrested because a gas station employee accused him of not paying for gas after he declined the receipt. Grocery stores and department stores, I want a receipt because there’s too much bullshittery and asshattery going on at those types of places for me to go without. I want to see when Walmart charges me $5.99 instead of $3.00 like it said on the shelf and I want the money back on my card when I inevitably have to do a return. Restaurants, I want my receipt because unfortunately some of the folks who run the card will “accidentally” miskey the tip amount, and strangely it’s always in their favor.
A disappointingly large proportion of the general population appears to be unable to tell the difference between centipedes and millipedes. Is it possible that the “centipedes” you saw were actually millipedes? If so, they may have been “fucking”, or at least the millipede equivalent of it.
Additionally, it appears that this “fact” is actually wrong (big surprise, huh?). Many species of centipede do have courtship strategies that involve males and females meeting up. The sexes may even employ various forms of physical touch as part of the process. So, it’s certainly possible that the critters you saw where centipedes courting each other.