Trigger warning 

A warning before showing something that could cause a PTSD reaction. Commonly used as a joke, its meaning has unfortunately depreciated, drawing more stigma to mental illness.

The teacher gave a trigger warning before showing us the rape scene in the movie.

Trigger warning by dogmom5678 April 2, 2017

Trigger Warning 

A phrase posted at the beginning of various posts, articles, or blogs. Its purpose is to warn weak minded people who are easily offended that they might find what is being posted offensive in some way due to its content, causing them to overreact or otherwise start acting like a dipshit. Popular on reddit SRS or other places that social justice warriors like to hang out.

Trigger warnings are unnecessary 100% of the time due to the fact that people who are easily offended have no business randomly browsing the internet anyways. As a result of the phrases irrelevance, most opinions that start out with this phrase tend to be simplistic and dull since they were made by people ridiculous enough to think that the internet is supposed to cater to people who can't take a joke.

Trigger warning: If you think this phrase needs to be posted before politically incorrect opinions, you don't belong on the internets.

Trigger Warning by pottskiller January 3, 2014

Trigger warning 

Used to alert people when an internet post, book, article, picture, video, audio clip, or some other media could potentially cause extremely negative reactions (such as post-traumatic flashbacks or self-harm) due to its content. Sometimes abbreviated as "TW."

Trigger Warning for sexual violence

Trigger warning by raggedyanndy November 9, 2011

Trigger Warning 

A word that makes me want to pull a trigger (albeit, of a difference sort) every god damn, fucking time it is uttered.

Trigger Warning

Urban Dictionary is not a website you want to be on if you are easily offended. If you are: Seriously, what the fuck are you doing here?!

Trigger Warning by Shingle My Wagon June 16, 2013

Trigger warning 

A phrase posted at the beginning of various posts, articles, or blogs. Its purpose is to warn people with issues such as PTSD, Depression, Suicidal thoughts/behaviors, past drug/alcohol addictions or victims of things like Rape and Abuse that there is content ahead that may trigger a traumatic flashback or could possibly even make them want to harm themselves ahead. Sometimes, for people who have harmed themselves in the past, just one picture or post about self-harm can make them want to harm themselves again.

Trigger warning are necessary before posts that have to do with traumatic events, such as rape, cutting, suicide, drug use, and other PTSD influencing subject matter. They should never be used as a joke or joked about (unless you are around people you know will not be triggered by it).

Before posting a picture of someone cutting themselves, one might include the phrase "Trigger Warning" before the post.

Trigger warning by SunnyDaylily March 3, 2016

Trigger Warning 

A trigger warning is a phrase included before a story, video, picture, etc. It's used to warn people of triggering words or pictures. For example, if someone has PTSD or MDD, this could be posted if it uses suicidal thoughts, or a traumatic experience. Some people say this is for oversensitive people, but is actually very useful if the story/picture/video has actual triggering words/scenes/thoughts. Can also be abbreviated to TW.

Trigger warning for rape and suicidal thoughts.

Trigger Warning by Nicole+ May 2, 2015

trigger warning 

A trigger warning is when something may make you feel emotional, like mad and upset
So at the start of a text, video, etc it my say 'trigger warning', it alerts the viewer that the content may make them feel ashamed, have a break down, etc.
the moral is that if you see trigger warning, just be prepared that your emotions may escape your mind :)

Example
If a video says trigger warning it may show suicide content, death content, racism, rape, etc

trigger warning by define me hoe April 24, 2018