Snape in drag
AbendrothBlutjager
black veil, or is Snape disguised as Pince? Did Snape actually attend
Dumbledore's funeral?
Remember, Mundungus wore a similar (maybe the same) outfit to the
Hog's Head back in OotP. It was the only way he could get into the
bar, since Aberforth had banned him. Apparently Mundungus has been
using this disguise for several years.
In PoA we have Neville's boggart change from Snape to Snape in
Neville's gran's garb. Later in PoA we have Dumbledore and Snape pull
a cracker apart, and out comes a witch's hat, which Dumbledore
promptly puts on his own head after Snape looks at it and refuses to
wear it.
In GoF we have the old wizard at the Quidditch tournament who wears a
Muggle dress because he wants a nice breeze about his privates....
In HBP we have Crabbe and Goyle Polyjuiced to impersonate girls,
wearing girl's robes, and all.
It seems fitting that Snape would also employ this tactic.
JKR said Snape would never have worn a turban (like Quirrell did), but
she never said he'd refuse to wear women's robes or otherwise dress in
drag....