It's a lighthearted way of wishing someone a good day, with a playful twist on the typical "have a good day" sentiment. It's not meant to be taken literally, but rather as a humorous way to express good wishes.
Here's a breakdown:
* Espero: I hope
* te la pases: you spend (informal)
* de pelos: hairy (literally)
* hoy: today
The phrase is often used amongst friends and family, and it's a way to express a bit of fun and lightheartedness.