Formal:
* The politician's ingratiating smile and promises did little to convince the voters of his sincerity.
* The new employee's ingratiating behavior, while initially charming, began to feel insincere after a while.
* Her ingratiating manner, while effective in gaining favor, sometimes came across as overly familiar.
Informal:
* He tried to ingratiate himself with his boss by offering to take on extra work.
* The puppy's ingratiating antics, including tail wags and playful nips, quickly won over the hearts of everyone in the room.
* She used ingratiating flattery to get what she wanted, but her true intentions were soon revealed.
Remember: "Ingratiating" often has a slightly negative connotation, implying that someone is trying to win favor through insincere means.