VorGuy will have me call ahead of time to a pizza buffet (if you are trying to feed a bus or two of teenagers quickly - buffets are the best way to go) to arrange the price for the group (and make sure that the bus driver is "free" - the usual perk around the USA for bus drivers - sometimes one or both of the teachers will be "free" as well, as I find out what the group rate is).
Then he has me call when they are about twenty minutes away, to make sure that they know that tables need to be cleared, dispensers of glasses & straws filled, and clean plates & forks put out - if they haven't done it lately (or if they are really busy, some places will start handing out paper plates and disposable cups - say they have four school groups coming in at overlapping times due to an event in the area). They also have time to slide extra pizzas in the oven and set up a few - just in case the hungry horde eats the buffet as bare as a cloud of locusts can eat a field).
He comes in, pays, the horde goes through at least twice - three times if the stop is long enough and then back on the bus to get back on the road to the next location (the school for pickup, hotels if they are on an overnight trip, or whatever). No tables are dragged together - 40 people (a bus load) is really too many for that. But enough pizzas for 40 people walking in at once -you need to have them ready or there will be NO food on the buffet and hungry looking people standing around, not a good thing.