Gabriella I’m afraid you’ve missed the point.
Of course knickers in themselves are rarely amusing.
They are only amusing in certain contexts, for example Katherine Whitehorn’s time-honoured advice about what to do if your knickers fall down at a cocktail party (step out of them as unobtrusively as possible, walk away, and pretend they’re nothing to do with you).
What I found amusing about the advert in the M6 female toilets was that the fart-busting knickers had the same name as a well-known breakfast cereal, which as annsixty pointed out, conjures up a stereotypical image of a curly-permed nanna busily occupied knitting knickers.
Some very clever marketing there, but I’m surprised that Kellogg’s haven’t spotted it and taken legal action.