wax poetic
To speak about some topic in a poetic manner, often exaggeratedly or verbosely so. The entertainer has a habit of waxing poetic during interviews, which delights some people and infuriates others. Dan always loves to wax poetic about his vacation to Peru.
wax poetic
Fig. to speak poetically. I hope you will pardon me if I wax poetic for a moment when I say that your lovely hands drift across the piano keys like swans on a lake.