It hits your prostate

You move just a bit to get some breathing room.

Big mistake. The move shifted the buffer in your ass to where it's rubbing up against your prostate.

Your dick begins to swell tremendously inside the vacuum nozzle.

The janitress reaches down and clicks up the speed on the buffer.

'Fuck, fuck' you think to yourself.

You can't take it, the tingling is too much.

Your cock explodes for all its worth. The vacuum sucks down every ounce of your cum.
The janitress rubs her clit furiously grinding down on you.
Then her juices squirt out onto your face as she moans in pleasure.