I would say that daybeds are NOT a girl thing.
We bought a daybed when my son was small, for a guest bedroom. It was a darker wood, with dark grain (sort of like a walnut or early american finish). Since it was for a guest bedroom/office, we found brown/green /tan manly looking daybed cover/pillow set
Since we have moved, we haven't used the daybed. My nephew is currenltly using the daybed. Incidentally, he is n't using the cover sheet set, since he is a little younger (he's only 3!)... but no its is a very masculine set