A sandwich of an inferior quality given to musicians - members of the band - entertaining guests of your boring event.
After I've been playing for over two hours at that middle age crisis wedding, they gave me one stale bandwich to eat and some half-and-half as a drink.
When a coworker asks you commit to going out to get lunch together, then said coworker betrays you by acquiring lunch elsewhere and not notifying you of their change in plans.
1. Steve asks Jason at 10:00am to go get Indian food with him for lunch. Jason walks into the kitchen at 11:45am and finds that Steve is eating a large sandwich, implying that he cancelled lunch plans with Jason in the rudest way possible.
2. "Aww man, I just got disandwiched by Eric. That guy is such a dick."