Okay, you're visiting Disneyland from out of state or not from the local area. You randomly run into someone you know.
How often has this happened to you?
On a recent trip, we ran into some workmates of my husbands who we didn't know would be at Disneyland. We actually walked right into them in Frontierland and then literally sat down behind them in DCA.
Years ago on a trip to Disneyland Paris we ran into a school friend of my middle son's (he was about 8 at the time). He actually runs into people he knows all the time, wherever we go - so that one probably doesn't count.