spontaneous erection 

The boner you get for no reason at all, usually happens during non-arousing times, such as english class or a funeral.

dang did you see how jim was walking? I think he was hiding a spontaneous erection.

spontaneous erection by ricky warden June 11, 2006

Kelly spontaneously showed up 

To be aroused sexually; to get a boner without expecting

Kelly spontaneously showed up when Jeris was on a road trip to Wyoming with the guys.

Kelly spontaneously showed up by CougarCrazies August 2, 2008

Spontaneous Emojiconing 

The use of iPhone Emojicons spontaneously through a text message. Generally a lengthy message, and could result in a "Spontaneous Emojicon War" through text between two or more people however a winner always emerges as it takes time to type each message and generally one person will quit and find something better to do.

Wow, you have a lot of emotion all of the sudden! Spontaneous Emojiconing that is!!!!!

Spontaneous Emojiconing by friendlesscoolkids December 7, 2010

Spontaneousnessism 

The act of being spontaneous.

The night did have it's spontaneousnessism's

"it slaps that"

Spontaneousnessism by BLITZ420 January 30, 2021

Spontanus

Noun

1. A portmanteau of the words "spontaneous" and "anus", it's a term used to describe shitting your pants suddenly and without warning.

"Please stand back, I just ate a hot mayonnaise sandwich and it might get spontanus up in here."

Spontanus by billebllunt February 12, 2014

Spontaneous Cumbustion 

The process by which, through the ingestion of an unruly quantity of phosphorous, one's ejaculate spontaneously erupts into flames upon expulsion from the penis causing widespread fear and panic.

Dave and Marie were dating until Dave's spontaneous cumbustion all over Marie resulting in a sudden case of the funerals.

Spontaneous Cumbustion by Diction.net February 24, 2015

spontaneous regularity 

(n.) diahrrea, often of the explosive and unpredictable sort.

What Donald thought was a fart had turned out to be a bout of spontaneous regularity.

spontaneous regularity by Blenderhead91 April 10, 2009