I was on an abandonware site, very likely looking for one of Sierra's "Quest" series games...I'd played them back in the 80s & 90s. I don't remember for certain, but it was one of two things. It was either a "This game has been removed because it is now available on GOG" message, or I saw some kind of banner ad. I don't remember which because I've seen both on many abandonware sites. I'd also say with maybe 80% certainty it was one of the old "Home of the Underdogs" sites (as there were a number of those)...20% chance it was Abandonia itself.
Its been like 4 years or so, I'm lucky I remember this much.