You don't have to,
but it's HIGHLY recommended.
The Big Bang Theory Season 3, Episode 2
And she's a HIGHLY distinguished
surgical resident at Fremont Memorial.
The Big Bang Theory Season 2, Episode 9
and able to anticipate your
actions, it is HIGHLY unlikely
The Big Bang Theory Season 5, Episode 7
SHELDON:
Highly.
The Big Bang Theory Season 4, Episode 4
Me, a HIGHLY
regarded physicist.
The Big Bang Theory Season 5, Episode 6