This is Halloween!

"- Dad! Wait, dad! Am I scary?
Vegeta stopped in suddenly and turn back to the voice. Trunks raced towards the footsteps of Goten. Vegeta needed a few sec before he realized what he sees. His eyes widened in.
- What the...
Trunks stopped in front of him and smiled excited. He wore a totally same clothes as his father’s normal wear, just the boots were a little bit strange on him. And his hair. He made it up, and it looked wet because of the hair gel.
- Am I really scary now, aren’t I?
Vegeta raised his right eyebrow.
- Come on, dad, am I scary now?! Am I? I want to be really scary!
- Me too! - said Goten suddenly. He wore a dark saiyan armor. A real saiyan armor with that stupid skirt-thing and shoulder pad, and the scouter... How did he get the scouter?
- Where the hell did you get that?!
Goten took a breath to answer but Trunks was faster.
- Piccolo made it!
- Piccolo...
- Ya told me don’t dare go near him so I didn’t ask him to make me clothes but Goten did!
- Because my brother sai...
- I really didn’t! - interrupted Trunks. - I’m not cheating! Because mom said she’s busy and can’t make my halloween costumes, I did it! So don’t get mad, but I had to cut your boots cause it was too big, and pin it with a safety pin, it’s looks cool now, isn’t it?
Vegeta 's face didn’t seem as if it would have been cool. Trunks didn’t notice it.
- So am I scary now? Cause mom said once you were the scariest man around the world and I wanted to be the scariest too, so I cosplayed you!
- And I made Turles! - interrupted Goten. - Cause my brother said he was the scariest man he ever met because he looked like dad, but he was so evil, and I look like dad too. And he also sai...
- So can I dye my hair?! Black like yours! - Trunks still didn’t realized the growing anger on his father’s face. - Please, dad, just one night! I’ll wash out it, I promise!
Vegeta didn’t answer. He afraid of if he does, if he moves just a little, the two brat wouldn’t survive.
- Please, dad, please! Just for tonight... Dad...?
Trunks finally noticed that Vegeta 's face oddly taut with anger.
- I’m sorry for the boots. - he gabbled.
- The boots.
- Yeah, really sorry! I’ll fix it! I promise!
- Fix it...
Trunks smiled at him apologetically.
- So if I’m not dying my hair, can I go super? Cause you got blonde hair too if you go super, so we could be the really same! Or am I scary as hell if I just made ya’ face, like this? Hmpf!
Trunks pursed his lips and looked up at his father frowningly.
Vegeta winced. Trunks stopped acting immediatly.
- Nevermind dad! Come on, Goten! - He grabbed his friend’s arm and he pulled him at the door. Goten looked at him confused but after he got over his surprise.
- Good night, Mr. Vegeta! - he said clear and loud, and followed his friend. Vegeta looked after them sullenly.
That two little peace of shit. What a shame...
Why does he do it? Why just don’t kill them and enjoy the silent forever...? Always the old story!
Don’t hurt anybody.
Don’t break anything.
Control your anger.
Take care of your son.
Don’t get mad if he made you a clown.
Don’t kill him for your boots.
Let him dye his hair, it’s just for Halloween night...

What the hell exactly this Halloween thing means...?"