This is why I love the Kids Next Door (Sector V specifically). They stick up for each other. Numbuh 4 is known as a jerk, but the others know he’s really a good kid underneath all that, and they’re willing to defend him. Especially because Numbuh 1 is also a good kid, and he should know better. (For the record, though, that isn’t Numbuh 1. It’s Negative Numbuh 1.)
And when Negative Numbuh One tries to pull the phony “Oh I was just kidding,” card, they have none of it. They want a real, genuine apology out of him. As Numbuh 5 said, it isn’t funny.