get under one's goat

Uncertain. Perhaps a blend of get under one's skin +‎ get someone's goat.

get under one's goat (third-person singular simple present gets under one's goat, present participle getting under one's goat, simple past got under one's goat, past participle gotten under one's goat or got under one's goat)

1. (transitive, figurative, nonstandard) To irritate or annoy someone; to bother.
   • 2013, Sherlyn Gajewski, Freedom of F-----g Speech Baby, page 105:

     Maybe you would have been warm when you died; You should not have gotten under my goat.

• The object of the verb is the possessive pronoun used: e.g. to get under his goat = "to irritate him"; this gets under my goat = "this bothers me", etc.

• get someone's goat