Mouthwashing in Public

I like to mouthwash. In fact, I mouthwash multiple times daily (when you include floride and pre-brush rinse along with the generic antiseptic). The tricky part is, I do not live alone in a studio apartment with a private bathroom. I live in a college dorm room with a shared public bathroom.

This bathroom is connected to my room by a very long and very public hallway. I keep the mouthwash in my room (it would get stolen or thrown out if I left it in the bathroom.) Thus the sequence of events is typically this: In my room I pour the mouthwash into my mouth and begin swishing. Then I walk, down the long hallway, to the bathroom, swishing in the meantime. There is about 20 seconds of swishing left (of the 60 seconds I do) when I arrive in the bathroom. Thus I stand in the bathroom, sometimes pacing back and forth, swishing the mouthwash until the total 60 seconds is up and I can finally spit it into the sink (usually my eyes are awkwardly red and teary at that point).

The awkward thing is passing someone I know (a loose acquaintance or "hall-mate") in the hallway. Although the swishing is loud to me, they certainly cannot hear it. It is also not that visually obvious to them what I am doing ("does he have a tick??"). So they pass me and say, "hey Clay" and all I can muster is "mmmhhmmmm!" (which means, "Hey Bill!) with a closed-mouth grin or thumbs up or something of the sort. These people are often incredibly confused as to why I suddenly lost my ability to speak and am now resorting to baby talk. Sometimes, panicing and realizing they think I'm a crazy person, i desperately try to explain to them that I'm in the middle of my Listerine routine and cannot properly great them but that only comes out as, "mmmhmmm mmmmm mmmhhmm mmmm mhm mmhm mhm mm mm mhm mmhmh."

The hallway is almost less awkward than seeing someone in the bathroom however, because one is not expected to have a conversation; a simple "hello" or "mmmmhmmmm!" suffices.

Sometimes I'll arrive in the bathroom with my 20 seconds left of swishing and see that person I know from class and whom I'm normally chatty with in the bathroom. He'll say, as he finishes washing his hands, "Yo what's up? What'd you think of that problem set?" At this point I am faced with a dilemma: do I spit out the mouth wash, clearly interfering with my routine and cutting my hygiene time short, or do I say, "mmmhmmmmm!" (which means "hang on one second") hold up a finger, requesting a moment, and then spend another 15 seconds silently swishing to myself. (I'm preemptively eliminating the option of trying to explain that "I thought #8d was hard but other than that it was fine" in gibberish). If I choose the former, it will be quite obvious to them as soon as I spit out that I was mouth-washing and cut my routine short just for them. They will then feel bad for having cut my precious 60 seconds short, and also think I am a bit pathetic for not having the gumption to bear the 20 seconds of ambiguous and odd silence to finish my clearly regimented oral hygiene routine.

The issue further deepens when the said bathroom mate greets me just as above (with a non yes or no question) and yet is drying his hands. He is almost done with his routine and practically on his way out the door. Do I make him stay an extra 15 seconds, standing there like a jackass, holding the door open, halfway between staying and leaving, just to hear the answer to a question he probably doesn't even care about and was just asking in the interest of making small talk? Or do I cut my routine short and spit it out early? OR do I, in an attempt to neither cut my routine short nor keep him waiting, somehow indicate to him, via a combination of hand signals and gibberish, that I am mouth-washing (and will be for the next 15 seconds or so) and to not bother waiting for me and that we will resume this conversation in the future?

I'm overwhelmed.