Characters: Sindy, Curious George, Bumble
Sindy (portrayed by model Pamela Vandenberg) was featured in numerous magazine and TV ads, from roughly 1999 to 2002, I think. She even had an official website, TooHot.com, though that has long since vanished. Later still, there was a fansite called "There's Something About Sindy," but that's now also gone. (You can see bits of it via the Wayback Machine, though. Or you could check AltoidsAds.com.) As for "the curious little monkey," I've never particularly been a fan, but he does seem the perfect choice to advertise "the original celebrated curiously strong mints." (Because they're both "curious." Get it?) And I have always been a fan of Rudolph the Red Nosed Reindeer, so it was neat to get a tin with the Abominable Snow Monster (aka Bumble). (There have been other character tins, but these are the only three I own.)
