Several I’ve been involved with:
There used to be a bakery in New York, called the Erotic Bakery. Among other things, they made gingerbread men / women with all the “parts” done in icing. We would get a pair of these when we had a wedding to go to, and persuade someone in the wedding party to smuggle them into the newlyweds’ luggage.
Unfortunately, on one such occasion, the smuggler took the opportunity to dump an entire bottle of some kind of cologne into the luggage as well. YUCK!!!
Naughty cookies: harmless. Industrial-strength stinkum ruining ALL your clothes? Not harmless.
Shortly before we got married, I made some chocolate dipped marshmallows for my intended. I ALSO made several chocolate dipped cotton balls which shared the plate with the real treats. Hilarity ensued.
I’m on an email list for parents of kids about my son’s age. One list member would typically post something outrageous but plausible about once a year on… April First. People would respond to the email as if it were real, until someone spotted that it was April Fool’s Day.
So one year, she was going to be away (without access to email - this was before smartphones) from late March into early April. Another member emailed everyone BUT this person, saying “hey, let’s prank her, I’ll start a thread on such and such and we’ll devolve into a flame war”.
It worked beautifully. Everyone responded as if it were a real thing, people would “take offense” at ridiculous stuff, and so on. I still don’t quite recall how it proceeded to jogging naked on a beach…
The original person came back from her break, and started catching up on her emails, and started messaging everyone with “Oh no!!! Let’s all calm down!!!” when someone quickly messaged her to let her in on the prank - at which point she conceded that it had been a masterful prank.
So I’d list this one as somewhat less benign given that she was pretty upset for a few, but it all ended well.