An asspull can be used to describe when, in a T.V show or Movie, the protagonist comes up with a never-before-seen power just in the nick of time, therefore winning the fight. An ass pull either has a completely unbelievable explanation or the writer conveniently forgets to add one in.
This is most commonly seen in the anime (esp. bleach and sailor moon) where the characters are all about to die, but then one of them (in those two, it's almost always Ichigo or Usagi) goes 'oh wait, I forgot about my superawesomeultramove that can kill all the bad guys'.
Basically, it's one of those moments where you're watching anime or reading a particular manga and something so stupid and logic-defying occurs you're left with a dumbfounded facial expression accompanied with a good ole "what the fuck just happened?"
5. Naruto - Itachi Uchiha using Izanami against Kabuto
So apparently, this is a genjutsu which affects the target through physical sensations shared between them and the user. In exchange for the temporary ability that it grants the user, the Sharingan with which Izanami is cast is rendered blind and loses its light forever. According to Itachi, this technique and Izanagi form a pair, but unlike the latter, which is a technique capable of altering destiny, Izanami decides your destiny!!! Yep your f-king destiny!!! You dun goofed Kishimoto!
You dun goofed
4. Bleach - Yammy vs Byakuya and Kenpachi
Yammy is THE strongest espada at 0 and regards ulquiorra and grimmjow as "trash" and you're telling me he gets trounced by byakuya and kenpachi both of whom had trouble dealing with threats lower than ulquiorra!!
Seriously, what the fuck were you smoking Noriaki Kubo?
Because I want some!!
3. Leorio from Hunter x Hunter
Am I the only one who utterly Hates this guy and constantly questions his existence in the manga/anime universe?
So essentially, he goes from this ...
To this...
He literally punched one of the top 5 nen users of the HxH universe in the goddam face.
I mean..
I can't even...
Fuck it.
2. Claymore - Priscilla killing Teresa via cheap shot
Teresa was always billed as the most powerful (known) character in the Claymore universe. Now get this, the only reason she lost to Priscilla was due to her...
Drum roll please ..
letting her guard down.
Teresa the prodigy, The one whose perception skills and yoki were so great she could critically injure the awakened top Claymore shortly after finishing her own Claymore training. The one who fought the subsequent Claymore No. 1 (who finished off the previous after Teresa injured her) with only 10% of her Yoki reserve only to die because of a f-king cheap shot.
I can't say much about this but ...
Yeah... I sat in front of my PC with a blank expression after the final fight.
No... Just no.
1. Fairy tale chapter 322
I dropped this steaming pile of putrid horse shit because of this chapter alone. I don't want to spoil anything but if you're to read it, I think you'd understand. I'm pretty sure that even this below gif wouldn't BEGIN to discern my initial reaction to this monstrosity of a manga chapter.
I literally had to take a good 20 minute walk to calm down. This chapter was an insult to my intelligence and if I ever catch Hiro Mashima on the streets, to say I would curb stomp him would be a understatement.
I'm sure there are way more (and much worse) asspulls that you've managed to come across and I'm fairly certain it must've left a bad taste in your mouth and if so, please feel free to share them.
. Made the scenes where they managed to do something sweeter though 
that's my nigga, then he runs away after running out of juice 
