Ayumu, upon being asked what's the name of "that cute girl with the braids", honestly, seriously thinks about it for 3 panels before admitting, completely deadpan, "I forgot."
Many of the manga 4-koma (bonus 4-panel gags). Especially Kanone and Eyes throwing knives.
Particularly the one explaining why Kousuke is continued wearing his glasses even after the lenses broke. He was about to leave them aside, when:
Rio: You absolutely cannot do that!
Ryouko: That's right!!
Rio: If you're not "blockhead four-eyes Kousuke," then you're no Kousuke of mine!
In Alive, Kiyotaka is the FASTEST FROG IN THE WOOOOOOOORLD. And green is beautiful.
And anything Imari does, really, especially when she takes the nunchuks out.
Whenever Kannone isn't busy being an absolute badass, he tends to be side-splittingly hilarious.