In Guardians of the Galaxy 2 when Peter has decided to fight Ego and he keeps destroying Ego's body, Ego eventually changes to David Hasselhoff saying something along the lines of:
I simply picked the form that would be most pleasing to you, would you prefer this instead?
As far as I recall Peter had never revealed to Ego that he used to tell people that the Hoff was his dad.
Can Ego read minds? If no, how else did he get this information?