I used to think the title of Savage Garden's "The Animal Song" was actually "Run through the Jungle" - fair enough, you might say. But I also used to think the line "I want to live like animals" actually said "I want to live like a cannonball". Thinking about it now, I realise it makes no sense, considering the rest of the song, but it didn't bother me at the time.
A childhood belief about misheard lyrics

others believed things like this
- I thought the song "Party Time" by Moby was actually saying "heart attack" (this was before I knew the title)— Elviessa
- Phil Collins song "I missed again" - I thought it was "I pis*ed again" - didn't realise he was an alcoholic?!Anon
- I used to think that the title of Barry Manilow's song "Looks Like We Made It" was "Looks Like Tomatoes".— close2nd
- I thought the song "Karma Police" was actually saying "call the police" before I learned the title— Alberto Richardson
- I used to believe eating fish enables me to live underwater and eating veggy makes me prettier!— Melody
- I used to believe that an animated film meant that the film had live animals in it.— reverb