Several assorted 'cultural' questions about Formula 17

1. When Bai & Richard return from the business trip, Chou's friends confront them and "spray" something on them. What is it? Seemingly it is just air, since there is no visible substance coming from the can, just the sound of air. But whatever it might be, what are they spraying or why? Well, the "why" I guess is to intimidate them into answering.... however any ideas are appreciated.

2. At the beginning, Yu sets up Chou for sex with the "Tapei Plumber." Chou is pretending to sleep and Yu comes over to the bed and lifts the sheet/blanket and very exaggeratedly "sniffs". What is he sniffing for? I have theory, but I would rather hear from others!

3. At the end credits, they are teasing Chou for wearing old-fashioned boxer shorts undewear. The friends each show their bikinis. They want the salesman at the store to show his underwear. He refuses. Yu seems to "encourage" him by rapidly moving his tongue in and out of his mouth. What kind of cultural expression is this ie is it Asian, Tapei, Taiwanese? Please explain. I've never seen this before.

THANK YOU very much to any and all to people who reply.

PS - I also wrote to Three Dots Entertainment a week or so ago, asking why they never had a sequel, no response. But I will certainly let you know here if they do.