I'll explain the jokes.
Chewbacca's grooming ordeal is an old gag, going as far back as the original '77 release. The idea of an eight foot tall sentient humanoid covered in hair is an interesting anomaly, moreso when one factors in what he has to do with all that hair. How does he maintain it? Does he groom himself? Does he shed? If so, does this present a problem since he is the co-pilot aboard a space pirate's prized starship? Indeed, Chewbacca is dog-like, and was intended to be viewed that way by George Lucas (alleged father of 'Star Wars') himself, who based the design on his own beloved pet at the time.
Seth Green, his writer and his producers have framed a 40 year old joke within modern parlance. Since Chewie is essentially an anthropomorphic dog, and pet grooming is a lucrative business in most American cities, he merges the two together.
Furthermore, science-fiction ('sci-fi') and Star Wars fans are often associated with the 'nerd' counterculture, and nerds are stereotypically depicted as being shut-ins who learn about sexuality and lesbian undertones from years of anime (cartoons for children produced in Japan but consumed by adults in the West due to a lack of Judeo-Christian ideology inflicted on Japanese television standards) and unsupervised Internet pornography. These two women, while in the process of grooming Chewbacca, have a 'lightsaber' (weapon used by 'Jedi' in the 'Star Wars' universe franchise) battle that includes using the 'Force' (a mystical energy field in the 'Star Wars' universe franchise capable of being manipulated by space wizards or potential space wizards who have compatible DNA.)
Since there is already water present in this scene, it provides an opportunity for Green and his crew to have the women's t-shirts stick to their wet breasts, creating a duet of identifiable 'Star Wars' nostalgia with overt sexuality from the typical sheltered nerd's point of view. The women appear to be getting aggressive and angry during their water/lightsaber fight, but there is more than a hint that they are enjoying the battle, because spontaneous lesbianism is also part of this mindset.
Finally, Green and co. end this piece by having Chewbacca covered in girly ribbons, returning the sketch to the original joke of the Wookiee (Chewbacca's sentient race) being a dog and having cute things stuck in his fur the way a pet owner's canine might. The ribbons can also be interpreted as standing in for kisses, since Chewbacca is male and what has just occurred was more or less a type of group sex.