Cell becomes Semi-Perfect when he absorbs 17. 16 tries to hold Cell off long enough for 18 to flee and gets half of his head blown off to thank him for his efforts, but Tien jumps in and uses a continuous loop of his Tri-Beam long enough for the androids to escape. With Piccolo down for the count and Tien permanently exhausted, Goku steps in and teleports them both back to Kami’s Lookout. Once they return, Vegeta and Trunks emerge from the Hyperbolic Time Chamber; both more powerful than ever. Bulma gives Krillin a remote which will deactivate the androids with hopes of it preventing Cell from evolving any further.
Vegeta arrives and can destroy Cell at any moment, but his Saiyan pride and the challenge of a more promising fight blinds him and Vegeta allows Cell to absorb 18. Krillin realizes he’s fallen in love with 18 and destroys the remote, but Cell absorbs her anyway despite the fruitless efforts of both Krillin and Trunks. Becoming Perfect, Cell stomps Vegeta into the ground and Trunks reveals that he has surpassed his father in the Hyperbolic Time Chamber but doesn’t want him to know about it. With Vegeta unconscious, Trunks lets loose but gives Krillin the last Senzu Bean and asks Krillin to take his father back to Kami’s Lookout to recover. While training in the Hyperbolic Time Chamber, Goku realizes that the second level of Super Saiyan is extremely strong but weighed down by bulky muscles and is ultimately a setback.
Before Goku finally steps in to help Tien and Piccolo, he declares, “This is the hardest thing I’ve ever done,” while sitting around and doing nothing. Oh man, doesn’t it suck having to wait forever for something to happen, Goku? The shoe being on the other foot is always more uncomfortable than you originally imagine. Imperfect Cell was pretty awesome, but Semi-Perfect Cell is beyond lame. He’s like a cross between a Battletoad, Ed Bighead from “Rocko’s Modern Life,” and a Beetleborg. As Cell is searching for 16 and 18, the androids take refuge on an island with a bunch of surrounding islands in the area. Since they don’t have power levels, they can’t be detected. Cell flies in and says he’s going to flush them out, but then takes a deep breath and spends the next five minutes yelling at the top of his lungs. What a monster. Do you think his breath was semi-perfect, too?
18 keeps asking 16 for advice, but then gets upset when he was wrong about predicting Cell’s actions. Lady, you’re the one taking advice from a guy who’s missing half of his head. You should be smacking yourself. Back at Kame House, Master Roshi lectures everyone to stay put and not help out because they’ll only end up dead. He then plops down on the ground with a confused look on his face and says, “Oh, poopie. What am I talking about?” That’s what we’d all like to know, Roshi.
As Trunks recalls his training with Vegeta in the Hyperbolic Time Chamber, he’s overcome by the extreme weather conditions in there; either extremely icy and dangerously cold or completely overcome with fire and unbearably hot. Vegeta is just seen yelling at the top of his lungs. So his training went from standing around and staring at nothing to yelling at the top of his lungs; this is progress, you guys.
One of the most ridiculous aspects of this show is that nearly every main and supporting character lives to fight. They thrive on the challenge of a good battle and train specifically for that. When the fight of their lives finally arrives, everyone suddenly doesn’t have time for it. The line, “Would you hurry up? I haven’t got all day,” is muttered over and over again. Don’t you? It’s not like you have anything better to do. None of these people have jobs. They train, fight, eat, make babies, and sleep; that’s it. Goku and Vegeta basically marry into money so they don’t ever have to work. So what else do they have to do? Cue Vegeta going Super Saiyan with six veins popping out of his head as he tries to knit a sweater.
Sources: dragonball.wikia.com, thedragonballblog.blogspot.com, tumblr.com, imdb.com, wikipedia.org, comicvine.com, funimation.com