There exists a group of moths called "underwings." These creatures have typical moth-y gray/brown-patterned forewings, but then when they fly or stretch, they reveal starkly contrasting hindwings, usually with super bright colors. The effect is almost more butterfly than moth, and totally unexpected!
I'd never seen an underwing moth before the following creature showed up at our porch light a few nights ago -- it's an underwing called (I believe) The Penitent (Catocala piatrix) (really, the names people come up with for moth species are just incredible sometimes):
Is that a cool moth, or what?? Some other species of underwings have bright pink on their hindwings, which is maybe even more shocking, but I like the way orange looks on this creature. Very pretty!