True meaning of 'come down'

[johno.]

I'm just curious about this because most people seem to be referring to 'come down' as the effects experienced the day after doing pills.

SWIM usually refers to the 'next day' effects as being scat, not coming down. You're already down, aren't you?

SWIM uses the term 'come down' when the effects of the pill are wearing off, and he is actually coming down from the high.

He could be wrong though, if so correct him. Discuss...