a person of Irish descent who, because of family money, is accepted into WASP society; tends to act, speak, and dress like a member of the upper-class WASP establishment.
That lace-curtain Irish bastard wouldn't last a minute in Southie.
Refers to Irish immigrants who, though living in shanties (shacks) would hold their airs and snobbishness. So called because they'd hang lace curtains in their tiny shacks.
My mom keeps the family silver in her double-wide, she's modern day lace-curtain Irish.