the Undertale characters were just chilling in the Hall of Judgement when for some reason and somehow they were transported to the universe of SCPs, and into the SCP Foundation Facility

Frisk:Ah where are we?

Chara:Idk

Toriel: I have a feeling it is dangerous here.

Sans:Yeah I don't think we'll have a Sans-sational time here laughs at his own pun

Papyrus:Damn it Sans, this isn't the place to be making puns!

Alphys:Hopefully someone can help us out of here

Undyne:on edge

Asgore:No need to be so one edge Undyne.