Grey's Anatomy viewers were treated to a pretty major trick on Thursday night's installment of this beloved ABC drama.

Yes, as you can maybe guess from that introduction alone, this was a Halloween-themed episode.

It was also romantically-themed, however, as Jo and Alex actually got legally married during the enjoyable hour.

Appropriate for the couple's last-minute Halloween wedding, the bride-to-be was dressed up like a corpse bride, while Alex donned vampire fangs.

The biggest stunner, however, took place when Jo revealed she was pregnant at the altar to freak out Alex... and, boy, did it ever work!

Thankfully, for his sakea tleast, she eventually admitted the truth.

Alex, for his part, was having a frightening day at Pacific Northwest, even putting aside this pregnancy scare.

The doctor discovered the construction for a new wing of the hospital was on a burial site ... and had several issues with patients.

All of this was going down while investors were visiting the spot to decide whether or not they should give money to fund the renovations, so the future of the project wasn't exactly looking bright for anyone involved.

Meanwhile, Jo spent all the entire day rocking her zombie bride outfit in order to lighten the mood and get Alex psyched for their nuptials  but Alex wasn’t amused.

Watch Grey's Anatomy Season 16 Episode 6 Online

However, when he somehow secured the funding for the aforementioned new wing, Alex decided to celebrate by taking Jo to the courthouse for their last-second wedding ceremony.

Enter Jo's prank.

While at the altar, she decided to freak out her new husband by saying “for richer or for pregnant” during her vows, achieving her goal and prompting a truly shocked reaction from her husband.

“Scared you! I got you so bad,” she said after, revealing it was all meant as a joke.

Elsewhere this week...

Meredith was behind bars after missing her court date last week, yet it wasn’t all bad.

Her inmate had a pretty horrible story about being arrested and having her kids taken from her that really touched Meredith; it helped her keep things in perspective.

When our favorite surgeon finally was released, she was determined to help and posted the inmate’s bail.

“I had a lot of time to think and I thought ‘Okay, if I don’t have a job and I don’t practice medicine, I still have a lot to work with and I’ll figure something out,’” she said to her friends when she returned home.

What, exactly, did Meredith mean by this?

It sounds like she may have a backup if medicine doesn’t work out -- and it also like she might be hinting at helping people outside of the medical field.

For now, though, we're simply left to find out (maybe next week?) if her medical license gets revoked or not.