I’ve just spent the last thirty years busting my arse off

This mix up can be heard by Gordon Ramsay on his Masterclass trailer.  It is a congruent conflation of “worked my arse off” and “busted my ass”, both meaning to work very hard at something.  The former idiom is heard primarily in the UK, while the latter is heard mostly in the US.  This malaphor, then, is perhaps an “across the pond” blend?  Maybe Ramsay spent too much time in Hollywood.  The posterior seems to be popular in malaphors.  To see more, type “ass” in the search engine on the website.  You’ll see such classics as “he was drunk out of his ass” and “you need to get your ass together”. https://malaphors.com/2015/08/27/you-need-to-get-your-ass-together/   https://malaphors.com/2018/06/28/he-was-drunk-out-of-his-ass/

A big thanks to Ben Glass who heard this one and sent it in.  You can hear the malaphor by clicking this link: https://www.masterclass.com/classes/gordon-ramsay-teaches-cooking