
It's MIDNIGHT.
The Big Bang Theory Season 10, Episode 11

Midnight.
The Big Bang Theory Season 9, Episode 15

The instructions are very clear.
Don't feed the gremlins after MIDNIGHT.
The Big Bang Theory Season 3, Episode 4

Midnight, really?
The Big Bang Theory Season 9, Episode 15

and later, the LEGO store is
having a MIDNIGHT madness sale.
The Big Bang Theory Season 5, Episode 23