Adding to khandu's way up there at the top:

when your friend and you figure out what key the cat sings in so you can pitch a song in its range, record it, and mix it in...

you don't write letters to your dad, just send him lyric sheets and printed out Mudcat threads with scribbled "I love you's" on the margins..

You know your SO is finally becoming one, too, instead of just an appreciative listener when you hear him sing for the first time in your 24 years together and it's his own made up songs for the dog!

all of your well-meaning family and friends, who don't really understand what music it is you're *into*, tell you about every possible concert, venue, gig, karaoke, etc. there is, expecting you to run right out tho them all...