Hope you bet a pizza on this one. Have your colleague read item (3) (or even act like Bart Simpson and write it on the chalkboard 100 times)
Code, section 414(q) (q) Highly compensated employee (1) In general
the term “highly compensated employee” means any employee who— (A) was a 5-percent owner at any time during the year or the preceding year, or (B) for the preceding year— (i) had compensation from the employer in excess of $80,000, and (ii) if the employer elects the application of this clause for such preceding year, was in the top-paid group of employees for such preceding year. The Secretary shall adjust the $80,000 amount under subparagraph (B) at the same time and in the same manner as under section 415 (d), except that the base period shall be the calendar quarter ending September 30, 1996. (2) 5-percent owner An employee shall be treated as a 5-percent owner for any year if at any time during such year such employee was a 5-percent owner (as defined in section 416(i)(1)) of the employer. (3) Top-paid group An employee is in the top-paid group of employees for any year if such employee is in the group consisting of the top 20 percent of the employees when ranked on the basis of compensation paid during such year.