Happy Mother's Day

Question for you – is Mothers’ Day spelled as a plural (like I just did) or is it singular as I have it in the title above?  For the answer scroll down to Spelling after you (click here.)

Then check out this parody of that great Geico commercial where the Mom calls her son when he is busy.
To Moms everywhere, enjoy your day. You have certainly earned it even if you do ocssionally call at a not-so-good-time.