Here is the full list of all 28 Tea Party Simulator 2015 achievements.
Get an 'S' rank in every level, in both Mode 1 and Mode 2.
Get an 'A' rank in all Mode 1 levels.
Get an 'A' rank in all Mode 2 levels.
Completed the fourth level.
Witness the potato box flying through space-time.
Activate the monolith.
Completed the final level.
Use the dynamite.
Use a frag grenade to end your tea party.
Completed the third level.
Completed the second level.
Activate the turnip.
Activate the snake.
Witness the zeppelin.
Witness the Red Baron.
Completed the first level.
Activate the sunglasses.
Let the chi flow through the spasticity of your hand.
Yes, well ... I'd call you a buffoon too if you poured hot water on me. Indeed!
Flip the bird, if the bird were a fancy bird.
Make a tea within a tea, or something.
Activate the top hat.
Activate the fish!
This hand ain't goin' nowhere.
Activate the calm book.
Why would you shoot ted?! He's your best and only friend!
Activate the aviators.
You really aught to do something about that stabbing habit.