sneak in vs spatchcock

sneak in is not a noun while spatchcock is a noun.

Word	Noun	Adjective	Verb	Adverb
sneak in	No	No	Yes	No
spatchcock	Yes	No	Yes	No

As verbs, spatchcock is a hyponym of sneak in; that is, spatchcock is a word with a more specific, narrower meaning than sneak in:

sneak in (noun)	spatchcock (noun)
	flesh of a chicken (or game bird) split down the back and grilled (usually immediately after being killed)

sneak in (verb)	spatchcock (verb)
insert casually	interpolate or insert (words) into a sentence or story
enter surreptitiously	prepare for eating if or as if a spatchcock