Wax poetic

[Sonia]

To speak or write about something in a highly eloquent or verbose manner. Comes from wax meaning grow or become as in the waxing and waning of the moon, thus to wax poetic is equivalent to to grow poetic. Thus to wax poetically doesnt really make sense, as it would mean to grow poetically, which isnt the same as to grow poetic.

[Becky]

To expound on something in prose like language. Wax as in the waxing moon means to increase, not originally a reference to vinyl.

[Luis Fok]

To wax poetic is the act of shitting on the baseboard heater and turning the thermostat up on the day you vacate your apartment.