lick someone's ass - Wiktionary, the free dictionary

From Wiktionary, the free dictionary

lick someone's ass (third-person singular simple present licks someone's ass, present participle licking someone's ass, simple past and past participle licked someone's ass)

1. Used other than figuratively or idiomatically: see lick,‎ someone,‎ ass.
2. (idiomatic, vulgar) To flatter someone (especially a superior) in an obsequious manner, and to support their every opinion.

• brownnose
• suck up