I just found these, I could make out some of it, what do you reckon? the beatles and led zeplin used to do the same sort of thing, I think it's called backmasking, pretty freaky shit I reckon
NIRVANA - ALL APOLOGIES BACKWARDS LISTEN AT 1:30
https://youtube.com/watch?v=mKGRv4Da6SI
NIRVANA - COME AS YOU ARE BACKWARDS REVERSE
https://youtube.com/watch?v=UUJGkXHR6oQ
NIRVANA - YOU KNOW YOU'RE RIGHT BACKWARDS LISTEN AT 1:38
https://youtube.com/watch?v=WU7M6cfBwdk