Green’s Dictionary of Slang

(orig. US) to act in an egocentric, self-aggrandizing manner.

1970		N.Y. 16 Nov. 6/2: Father ego-tripping on his children’s academic and other achievements.
1971		T. Lewis Plender [ebook] But they [i.e. adulteries] meant nothing to Peter. Just… what do they call it now… ego-tripping?
1977		C. McFadden Serial 28: You had to stay really in touch with yourself if you were going to relate to the other person’s feelings instead of just ego-tripping.
1991		R.G. Barrett Between the Devlin 161: [A]part from putting up with Quigley’s ego-tripping the work was pretty easy.
1994		N. McCall Makes Me Wanna Holler (1995) 117: Some of it was just plain immaturity. Like ego-tripping.
2003		G. Wood Tales from Country Music 60: Not an exercise in ego-tripping, it’s a case study of a creator seeking to improve his artistry.