You can always go with the 'feed the imaginary fish for a month' approach, that might be more appealing than 'piss in your fish tank' . That's pretty easy to understand too, although I don't think fishless cycling is that complicated (lots of manufacturers apparently do otherwise they might recommend it more). The main problem is that it takes so damn long, people don't want to wait 6 weeks. It would be better if aquatic stores would sell you a bit of mature media when they sold you a tank.
I did the most basic fishless cycle ever for my first tropical tank. Cut up tights, wrapped 4/5 good pinches of fish food in each bit with elastic bands, threw one in every few days, fished one out every few days so there was always 2 or 3 little parcels of food in various stages of decay in the water.
Of course being a fish geek I tested my water every day but obviously you don't have to make a chart with graph paper and plot the levels follow it so closely. You could just chuck in the food parcels for a month or so and test then. It's not exactly complicated.
In fact I wonder if you could fishless cycle using those holiday food pellet things?
I told a friend of on fb last week as she had bought a tank and was going to put ish in the following week (after the water had settled) . She probably thought i was being rude and probably thought i was a fish geek but hey ho .
Good luck! A lot of people would do a fishless cycle if they knew about it but sadly some people don't think it's worth the wait. It saves so much trouble in the long run though, cycling with fish in can cause all sorts of health problems and you end up spending money on various meds to sort out illnesses that you could've prevented if you'd just waited a few more weeks...
I dunno, I'm a fish geek, I'm lacking in social skills You could say something like, 'hey, I heard you are setting up a new tank and I saw this and thought it might be helpful'. Probably better than 'hold it, fish murderer!'.
A week is only just enough for the ammonia to peak, it takes about 4-6 weeks for the nitrIte to disappear too. This is a good explanation. Lots of shops say 24 hours, 48 hours, 3 days, a week etc. but most of them don't even tell you to add a source of ammonia. Leaving it empty does bugger all, even if you did leave it for 6 weeks.