The recent update iMessage on iOS causes certain words to trigger screen effects. Also, there is a way to long-press on the send button, and bring up an interface for adding these effects.
I've found the following associations between screen effects, and the messgaes that trigger them:
What is the list of these?
Also if you hold down the send button you can access a set of effects you can add to your message like a (Slam/Loud/Gentle/Invisible Ink). Now if you hold down the send button, not only do you get those set of effects, but the effects above with the SHORT list of trigger words are accessible at the top of the screen.
Just add to the list if you find some triggers. No need to remove the obsolete, as in some OS, they might still be working.
Congratulations! coloured paper cuttings
Happy Chinese new year! works in other countries too.
Happy new year! different from above.
Happy Birthday! balloons.
Pew Pew lights in different colours
Eid Mubarak Shooting Star
For iOS 10.2, the messages in the question are the only ones I could find that trigger a full screen effect, no others have been confirmed in the sources I looked at (Apple, iMore, iGeeksBlog).
So our list is:
Given that I can't find evidence of any other "trigger messages", I think it's safe to say that these are the only ones.
The words...
Best wishes shows 2 hands giving some stuff out. XOXO shows some hearts