This is not totally unusual, although I try to do it when nobody's around (although for some reason, when stoned and playing Magic, I lapse involuntarily into a tuneless little song that goes "I'm a squid...happy squid...wiggly squid..." to the point that those also stoned and playing opposite would begin coming in at "Happy squid" because...well...y'know.) So I found myself singing, and after a minute, realized that the catchy little tune I was mangling was--god help me--"Joy to the World."
Like most fundamentally grumpy people, I loathe and resent the encroachment of Christmas, like a fearsome gerrymander, onto the rest of the year. I resent its annexation of Thanksgiving, and I live in fear of the day it finally engulfs October, leaving the lone fortress of Halloween untouched, a stalwart hold-out against the red-and-green-dimmed tide. This is not a new complaint, every stand-up comedian from here to the Outer Hebrides has commented on this, but hearing myself lapse into carols in mid-October was a cruel shock. I have met the enemy, and it is me.