1. When you give someone a facial (that is, treat or serve them) and it's all smooth hence buttery. Giving someone a buttery facial may include, but is not limited to: using large, sophisticated words; being very clever and well thought out; and may take a few good seconds for the average person to understand.
2. When you spread butter on someone's face for whatever reason.
1. Damn, he gave me an uber buttery facial. It was really well thought out and it used all these big words like "incomparable." It really made me feel bad... :(
2. I was really bored so I decided to spread butter all over my face. I gave myself a buttery facial.