Process of elimination

Kacia found this punctuation travesty in a small restaurant in Wisconsin, on an ad for a business that does fireworks displays.

There has to be a logic here.  Let’s see.  Oh, you use apostrophes to pluralize!  No, can’t be that, because “weddings” and “graduations” are plural.  Is it a rule that you have to use an apostrophe after a y to pluralize?   Nope, can’t be that, because “birthdays” has no apostrophe.

I give up!  Thanks, Kacia!