The jealousy and possessiveness will be through the roof.
Either they won't be able to concentrate on that glorified filler, and Mok-yeon may tap out and leave. OR Mok-yeon will lose it when Nanjo does something with filler-uke, and possessively try to enter/kiss/other* with Nanjo, in front said side trash. OR they both go through with it, half-heartedly, with that chicken leg in the middle but maintain consistent eye contact during the whole thing, unable to get off without doing so and then meet up after the "threesome" is done, to really get off. HOWEVER, i'm hoping... Nanjo will be the one to get possessive and jealous(possible take action unconsciously), as Mok-yeon just tries to get through it, using his anguish over the situation as fuel to bare with it.
...mmaybe it'll be like tgat double penetration situation they had before and thus time when Mok-yeon leans forward, Nanjo kisses him.
Or it could end in a spat, where Nanjo is angry that Mok-yeon did the regular rough things with that chicken gizzard, not knowing that Mok-yeon was really only using it to vent his frustration about the threesome, and Nanjo confronts him...
Bwhaha. I loved this, all the different names got me rolling!
Sooo we all agree that the "party" is gonna be a complete and total disaster, yeah?