@Celiohogane
He probably just thought it looked cool, but got so self conscious about the brother accidentally pointing out that the former also thinks it's hot. Then he just had to commit to the bit.
@OmegaDragon
She wanted to clear the mission and get away with not having to do the horizontal tango(at least until she leaves the body). She didn't count on the guy to be that easy.
@Ncararc
I thought the "they actually skipped over a lot" line in the following chapter was the gag. I kinda wish they did just skip over, it was pretty hilarious, though unintentional.