jQuery CDN HTTPS certificate expired earlier today... and it broke a lot of sites! Happens to the best of us, but let's use this as a good reminder: go check when your certificate expires, and set a few alerts in your calendar spaced out a few weeks before.
You don't want your site throwing these kinds of errors. Also, while you're at it, do a quick audit on the third party services you rely on.
P.S. The jQuery team has already fixed the certificate error.