I don't have very many lyrics because I don't sing, but those few that I do have are indelibly burned into the brain.....but tunes, now that is different from lyrics. Usually, my "fingers do the walking" for tunes and I can look at the audience, dance, flirt, giggle (anything except talk) and I am fine. However, once in a while, I just totally blank out....and the only way to get back in is to get out completely and wait for the beginning.
Learning a tune is also different for lyrics people vs. tune people. I can learn a tune without lyrics, but I can't seem to learn a tune that I know has lyrics. With some people it is just the opposite. For our mando player, a tune MUST have lyrics (that she can hear in her head if all else fails) in order for her to learn it.
Her husband, the guitar player, does NOT want to hear about lyrics--he is a "tune" person like me. We seem to remember intervals or patterns instead of words. Does this make any sense at all?