guess my two favorites
Hint: they sound about the same, but appear unrelated

Battle against a true hero
(Definitely didn't look at the other comment)

lol

It is a good song though

Spear of Justice

close (i think)

Ohhhhh Battle Against a True Hero?

yes

Yess

Ghost fight and dummy?

no

Sans I just snorted a suitcase full of coke and I’m starting to feel the effects, Neh He hE

best undertale meme ever

Ye

I already know from the other comments
Guess mine (it's a combo of two that always go together)

NGGAAAAH! And spear of justice?

Nope
It plays at the very end of pacifist

Hopes and dreams and SAVE the world?

Nope

It's actually impossible to hear them separately in the game