That's what the well does. It is quite literally a wishing well. I stayed free of it myself, but several friends weren't so lucky.

[Hmm, it seems the song-spell can be broken if someone manages to lever in a change of topic, as long as it's somewhat relevant to whatever's being sung about. That's good to know.]

One of them wished to be...how did she put it? Less conspicuous? It turned all her clothes to camouflage fabrics. Quelle horreur. There was nothing I could do to fix them, either, and I tried everything.