2-A person who kisses up (see definition 1)
3-To date someone in a much higher social class than you. Often spelled 'kiss up'
4-A person who dates someone in a much higher social class than them.
2-James is such a kissup. He gave our teacher Mrs. Blow oral just so he could get an A.
3-Did you see Moriah kiss up? He and that slutty cheerleader Emily were making googly eyes at each other all through that test!
4-Moriah got lucky, the damn kissup. He was sucking Emily's tits behind the gym.