Harley Quinn Wiki

Oh, sure. You remember the incarceration date of Porn Clown over here but not your own son's birthday!
— Debbie Day.

Debbie Day is Julian Day's estranged wife. She makes her first and currently only appearance in "Til Death Do Us Part" where she along with her son visits Calendar Man while he is in Arkham Asylum.

She gets frustrated when discovering he knows the exact amount of days that Harley Quinn has been in Arkham for, yet has failed to remember his when his son's birthday is. He tries to tell her he knows it's "June-ish" although that answer does not seem to satisfy her.