#1. You're at an event and someone want you to hook up their iPod to your system for a song you don't have / know.
Even I am not so cheap to use ipods... no place to hook one up so NO is an easy answer
#2. Someone other than the client wants to use your microphone.
Unless she is hot and bear chested not going to happen. Most of the time it's a drunk and he just wants to yell and spit and spill his beer on me and the mic.
So no. If they take the mic, I kill the mic volume and turn off the receiver. Most of the time I wear a head set so they don't ask.
#3. Folks want to browse your CD collections.
What CD's? I have about 20 Burned CD's of top songs if the laptop goes down, other wise it's all data base driven.