[:] OR [:|] Meaning in Chat or Text Messages Online

When someone types [:] or [:|] in a chat or conversation, they are using an internet slang known as "Robot." This term is typically used to express the idea of being emotionless or robotic in certain situations. It can also be used to suggest that someone is displaying mechanical or automated behavior.

Example 1:
Person 1: How can you be so calm in the face of all this chaos?
Person 2: [:|]

In this example, Person 2 is using the [:|] emoticon to suggest that they are being robotic or emotionless in their response to the chaos around them.

Example 2:
Person 1: I can't believe Sarah broke up with me over text.
Person 2: [:]

Here, Person 2 is using the [:] emoticon to suggest that they are not particularly emotional or affected by the news of Sarah's breakup with Person 1.