I don't think bean dip was ours. I found a thread that discussed that one, and someone said, "It looks like it wasn't an eHell coined phrase, maybe a regional variant, due to how easily it is understood. A Google search turns up no results before 2000, with the earliest being 1 result in 2002, 3 in 2003, and almost no further usage until 2006 or 2007, where it seems to have sprung into popularity.
AKA, I don't think it's from eHell, but I do think it's from a local, English phrase."
Thanks for the reference. For giggles, I'm doing a couple of others.
A date range search for "What an interesting assumption," only returned one result, in 2001. Though the date searches are by no means an accurate reflection of the English language, they do give a pretty good idea.
(My range searches are currently between 01-01-1991 to 01-01-05, giving me a 14 year range and around the time eHell switched to its new forums-- within a year or so. Don't remember specifically, only I joined shortly after the move.
BTW, the only usage of the phrase seems to have been in reference to an inflatable bra, and someone calling out "What an interesting assumption that no one wants smaller breasts." Which seems to be in context to the current phrase, but might be unrelated except in words and spirit.