el loco / loca (adjective, noun)

Frequency star
  1. crazy, mad, insane
  2. madman, crazy person
  3. fantastic, wild, amazing (colloquial)

Esa idea suena un poco loca, pero podría funcionar.

That idea sounds a bit crazy, but it might work.

Dirán que estamos locos.

They will say we're crazy.

Ni loco pago tanto por un paraguas.

No way am I paying that much for an umbrella.