He's the Gaster Blaster Master.
The first time he did it, it was a Gaster Blaster Master Disaster. He had to use a Gaster Master Blaster Disaster Plaster to clean up the mess faster after.

S T O P

as in for the comic it came from

NO

Well, not the original but I see what you meant. I'll put a caption of the whole original comic below:

Papyrus: Sans?
Sans: Yea?
Papyrus: Can I ask you a question... about your special attack?
Sans stands there for a second, nervous
Sans: yea..?
Papyrus: It is called a Gaster Blaster, yes?
Sans: mhm.
Papyrus: does that make you a... gaster blaster master?
Papyrus snickers
Sans, in his mind, "oh, HELL yes."
Sans: it's magic though, so I guess you could call me a gaster blaster master caster.
Papyrus: >:(
Sans: the first time I tried it though, it was a gaster blaster master caster disaster.
Papyrus: >:(((
Sans: it was such a mess, I had to use a gaster blaster master disaster plaster.
Papyrus chucks upward the snow he was trying to make a sculpture of himself with.
Papyrus abruptly says while doing this, "STOP"
Sans: ..after.

I know.

actually papyrus probably doesn't know about sans's gaster blasters because the gaster blaster is a human-killing weapon designed by Dr gaster and was given to sans

So it comes from sans's background of
At one time being the royal scientist

Which he would probably keep secret

-🤓

Can't argue with that

Majority of the fandom will
But I'll let them find you

Ok

You're the only one who's posting quality content here
Just so you know

*BZZZZUW PAHH*