Hi Fi

Hi Fi = High Fidelity. Originally used to refer to the quality of record players; in fact, record players/stereos were referred to as "hi-fi sets."

High Fidelity is also a book by Nick Hornby about a dysfunctional, obsessive record collector (a triple tautology!), and was made into a film starring John Cusack.

The term Wi Fi is a (bad) pun on Hi Fi.