Discord is great for keeping in touch with your friends, but that doesn't mean every message you send is appropriate for everyone. Luckily, you can use spoiler tags to hide certain messages.
Spoiler tags apply formatting to Discord messages in your browser, the Discord app for Windows or Mac, or the Discord mobile app for Android, iPhone , or iPad.

Adding Spoiler Tags to Discord Text Messages
There are several ways you can add spoiler tags to text messages you send on a Discord server. You can follow the steps below on any platform, including the apps for Android, iPhone, or iPad.
To add a spoiler tag to a text, type “/spoiler” at the beginning of a message. Sending “/spoiler this is a spoiler message” to a Discord server will hide the message until recipients decide to view it.

Alternatively, you can type two vertical lines at the beginning and end of your message. For example, “||this is a spoiler message||” will also appear as a spoiler.

To view a spoiler message in a Discord chat, click or tap on it. The message will appear highlighted with a gray background behind it.

Add Spoiler Tags to Images or Attachments
You can also add spoiler tags to images or other attachments that you send to a Discord server. The methods above won't work for this type of content, but you can mark files and images as spoilers before uploading them.
Unfortunately, you can only add spoiler tags to images or attachments you send through the Discord website or the Windows or Mac – they are not supported on the mobile apps.
To do this on the Discord desktop app or website, drag and drop your file onto the server chat or click the plus sign (+) next to the chat bar.

A preview of your attached file will appear before it is sent to the chat
Select the “Mark as Spoiler” checkbox to hide the image or file after uploading, then click “Upload.”.

After uploading, the image or file will appear in Discord behind spoiler tags. You can tap “Spoiler” to ignore the spoiler view and review the file.

This removes the spoiler tag and displays the image or file as usual.
Source: howtogeek.com
