I pulled under a shade tree one time many years ago to sort my next 50 stops. I had an old FM radio in the cab that was tuned to a 70's station, and the song "Brandy you're a Fine Girl" came on so I sang along to it while I sorted. The next song was "Dream Weaver" by Gary Wright, and I really got into it, my voice cracking on all the high notes as I screeeched out "Dreeeeeam weavah weavah weavah" with all the reverb echo. The song ended as I got my last shelf sorted, and when I went back up to the cab I discovered to my horror that a customer had been standing there the whole time waiting to ask if I had a package for her. She was trying to be polite but she lost it and just busted up laughing. I wanted to die of shame. That was the last time I ever sang along to the radio while working; thank God this was before smart phones and YouTube!