1) Kissing Distance close. When a person gets super close to your mouth and they are within kissing distance
2) To close a kiss, aka lock lips for the first time
3) If unwelcomed can be invasion of personal space
"OMG so like whatevs, Joe and I were hanging out and he got like KD close, but he didn't K. What an asshole"
"I know my doctor is supposed to examine me, but he got kd close. It was so awkward."
" She did nothing. I was KD close and she just stared at me. I need you to come to the bar next week with us and be my wingman."