In true JetPunk style I would like this opportunity to nitpick XD "In what language was the "Numa Numa" song sung in?" seems redundant. Too many in's I think.
My first solo trip overseas was the summer of 2004. I went to Europe and spent most of my time in Poland and Romania. Dragostea din Tea will always remind me of that trip. It was inescapable that year. I didn't think it would catch on in the US. A few months later I started hearing it in Virginia, too.
My most memorable European trip weird earworm tune was "The Rigga-Digga-Ding-Dong Song", which inexplicably got nearly as much air play as Cher's "Believe" in the summer 1999 in southern Croatia. The video is equally peculiar, if you want to amuse/torture yourself.
Gene Simmons is famously not drug-addled, in fact he claims to have never indulged in drugs or even cigarettes, and claims never even to have been drunk.
Any reason some of these questions are worded in the past tragic tense? It makes it sound like the Jonas brothers and Lady Gaga are all deceased, that Coldplay broke up, and that Shakira's hips suddenly started lying at some point. (Kudos on the wording of the Justin Nieber question though! Too bad you couldn't have situated HIM squarely in the past tense.)
Maybe change the clue for this one or come up with another question