Never seen that before

A few trips ago, my coworker and I were waiting to board our flight back to Denver from Seattle. He poked me and pointed out the window. Two firetrucks had pulled up facing eachother across a nearby gate. OK, that's a bit odd.

Then they both turned on their massive water jets - pointed up and towards eachother. Could that be an emergency? Highly doubtful. Even a drill didn't seem to make sense to me since the water wasn't aimed AT anything, but at the other truck. Almost like a water balloon fight between the two trucks.

Then a plane arrived and approached the gate -- and neatly traveled under this water bridge.

Have no idea what it meant - neither of us had heard of this type of ritual before. But we chose to speculate that the pilots had gotten married enroute. Hee. Or - a little less romantic, maybe the pilot was retiring or had just made his XXXX landing. Who knows - but it was certainly cool enough to entertain us for a number of minutes.