slackerade
Masquerade yourself as fictitious user on slack
Usage
slackerade https://hooks.slack.com/services/CHANNEL/URL/HASH USERNAME MSG EMOJI_NAME
Note: to have access to the channel Webhook Url you must first activate slack legacy Custom Integrations feature as explained here.
Install
pip3 install slackerade
Example
slackerade https://hooks.slack.com/services/<censured> "The Joker" "That's the joke" ":thats_the_joke:"
gives :
Notify the APP tag next to the username so it can be distinguished from a real user.