"What does that mean"?

[Bright_Star]

One of the owners of the diner put up a sign that says "Open usual hours during holiday weeK" to let people know that we're not closing early or staying open longer.
She said several people looked at the sign, then looked at her & asked "What does that mean"?
Shouldn't that be obvious?....lol.

[Lachrymose]

Maybe they read it as "unusual"? (Which would be hilarious, really)