For the ones who don't know what Gaster said here is a little translation.
"Time to die pun fucker "( sorry for the swearing)

xD

I feel like I saw this cat before...

Gettttttttt dunked on!

;0 are a little filthy lier Temmie

xD

Still as a baby he was making jokes

You need to know how to share sans... In my personal opinion I like flowey better ;3

Undertale papyrus + Storyshift chara = idk da name ;3
See ya next time toodles~