Humbuggery

Supersonic sleighs do seem
Slightly out of whack to me
As if in some fever dream
Huge impossibility
Was just swallowed, but once waked
All slipped off and was forgotten
Or when thought of, seen as faked
By the mind, and thus begotten
Only out of last night's cheese
Sitting oddly on the liver:
Must all presents under trees
Have a single, saintly giver
Or can we admit the thought
Of the presents parents bought?