I let it roll over my head

This seems to be a blend of “let it roll off my back” (not to worry about something done or said) and “roll over” (acquiesce to),  both indicating passivity.  The speaker may have confused the anatomy (back and head) which seems to be common in malaphors.   Also the two confused words are four letter words.  The phrase “roll with the punches” (go along with the program) also could have been in the subconscious as it is another phrase involving passivity or acquiescence.