'I forgot not to have sex with the groom's mum': Welcome to the biggest wedding fails.

Planning a wedding is hard. You have so many balls in the air it’s inevitable that something is going to drop. Thankfully, for most people, the ball on the ground is something like a pen for the guestbook.

Redditor WhiteSuburbanKid5 posed the following question to the members of r/AskReddit: “What’s the trashiest wedding you’ve been to?”

Let’s just say some people are forgetting much more than just a pen.

Oops, I forgot not to have sex with the groom’s mother

“The best man screwed the groom’s mother between the meal and the dancing,” writes wedding photographer ooohcoffee. “The groom finds out and punches the best man, breaking his hand. The best man drives away and gets stopped by the police for drunk driving.”

Oops, I forgot I don’t want to get married

“I was at a wedding in Germany once, and the bride asked for a divorce during the reception,” writes wickedlizerd.

Image: iStock.

Oops, I killed everything

"Some hippie friends of my parents got married when I was about 14, and it was a location wedding at some earthy little mountain getaway in Tennessee," writes ScottGreen1 "Only it was outside and in mid August, and in Tennessee that's like...90 degree, full humidity weather. But that's okay. Since it was so hot they decided to do it barefoot in a creek. Well they had a cage of butterflies to release during the kiss, but as it turns out, they had all died because of the heat! When the big moment came, someone opened the cage dramatically to let them free and like two half dead butterflies stumbled out and the rest were shriveled and dead inside. The hippie bride screamed in horror."

Oops, I forgot to hire a caterer

"My cousin who, let's say, isn't playing with a full deck and thought that she had hired a caterer because she sat at a bar one night and said to this lady 'you should do the food for my wedding'," writes Syble_Gable. "Waited until about an hour after the food should have logically arrived before starting to make some phone calls, only to find out that the 'caterer' was on vacation in Costa Rica and had no idea that the bride thought she was doing food for the wedding. Dominoes to the rescue about two hours later. But the reception being at a bowling ally with a keg in the middle of the dance floor was completely planned."

Oops, the wedding is Kid Rock themed

"My aunt married her third husband in Waffle House in Atlanta Georgia," writes Daria420. "They chose the booth where Kid Rock was once arrested."

Basically, just make sure you have these things, and the others listed in the Reddit thread (which you can view here), covered and you've got this wedding thing down.

This article originally appeared on Mamamia's US sister site Spring.St.