We Got An Air Plane Everybody

Gaster tries to make baby Sansy less angry by making airplane sounds while feeding him
and all the Sans-motions are wowed (well except Fellger) XD

you need to watch "inside out" to get this ^^

underswap sans as joy
inktale sans as disgust 
underfell sans as anger
negatale sans as fear 
monofell sans as sadness 

(like I said, this idea is very old, around a mounth or so, and I made lots of sketches around it so expect to see more)