The last time we went to the zoo, we decided to eat lunch at a picnic table outside. (The past few times, we had eaten in the cafe, with highchairs.) Unsure of how the twins would do - they prefer to get up and leave once we set them free of the stroller - Keith pushed our double stroller up to the seating part of the picnic table.
I cleaned it off with a wipe (which probably didn't do too much because it was wood, but it made me feel better), then added our table-top covers.
Now we do this anytime we want to eat out somewhere. The twins love it, and mommy loves not having to chase the children down during lunch!