I mean it was confirmed by him drinking it in the game oof

Ikr, and also, it was confirmed by the creator of UNDERSWAP

DT!Sans: ughhh-, hes...nevermind..$<"*...

DT!Sans: U-UH NO (Paps hide jfc-!)

DT!Frisk: Yaaayyyy!! You got itt!!))DT!Sans: Ok -.//-. Jeez

DT!Frisk: Man, this is..."KILLER"))DT!Sans: anddd she just made it obvious

DT!Sans: hes not a murderer or apart of the Killer crew, His name does start with a "K" though

DT!Frisk: Hint: Hes apart of the killer crew and he's possessed-))DT!Sans:*sighs* Ima kill you later Frisky-

Oki :]

Ok, Oof, I wanna die

DT!Sans: pff

Stab me

DT!Sans: Nothing, except get EXP

DT!Sans: Nightmare,Error,Killer,Horror, and Cross are sanses you fucking I d I o t

True, also, PIAB DONT DO IT-

DT!Chara: all of us are jerks Azzy-))DT!Frisk: Yup-))DT!Sans: correct

DT!Sans: no, it's only Sanses you nonce-))DT!Frisk&Chara:*LAUGHING*

DT!Frisk&Chara:*laughing at Chara* Pfff-))DT!Sans:*texting the killer crew: "Yo what's up, we gotta mission today or somethin?"*

DT!Sans: jesus, you're worse than Paps-))DT!Frisk: rude, but ok

DT!Sans: I'll talk about what I want, I could kill you, you're just the...Tu-TORIEL))DT!Frisk: PFF-