ALL CREDIT GOES TO HarpCity, ManicMetalHead, CGS Emo Muppet, and Our Afflictions. I am reposting this from their walkthrough solutions just for a simple access to the above achievement. I DO NOT TAKE ANY CREDIT FOR THIS.
From their walkthrough
, here is the portion that talks about it. Note: This has to be done in one game.
Quests are what have been appearing in the top right-hand corner of your screen. These are all relatively simple to complete and will change every 2-5 minutes, or after you complete one. Furthermore, quests will likely repeat, and completing them again DOES count towards your total of 25.
You can check your progress on this in your "Death Stats" in the cn_start menu. If you feel like you need more than 2 minutes, you can activate the "Wheel Goat" mutator if you unlocked it from the MMO DLC. If you choose to do this, you need to deactivate the mutator to gain a new quest, as well as to move objects around.
List of all quests (in alphabetical order):
Make something explode by headbutting it (e.g., canisters, cars, etc.)
Same as above, but 3 times
Craft the Gumshot (gumball machine + beer bong)
In the Mall, ride a bumper cart with cn_Y
Infect 3 humans
Craft an item
Don't Drop the Soap!
Enter the shower next to the house with all the pumpkins (by the goat pen)
Eat 5 food items
Bring money to the Fortune Teller tent at the Circus
Goat on Wheels
Craft a vehicle (craft either a bumper car or a skateboard)
Kill a zombie elephant
Craft a campfire (torch + stickman)
Win the High Striker game at the Circus (get to a really high altitude and land on the Striker while licking the hammer)
I am Goat
Enter the Goat Pen ("I am Goat" achievement)
I can see my House From Here
Jump from the tower on the hill near the Studios, and land on the car on the road
I Goata Party
Go to "The Allright Show" building, climb the stairs, and headbutt the handle
Unlock Prototype Goat mutator (stand on the electric chair on the roof of the tall orange building)
Craft and ride a skateboard (plank + skate sign)
Craft the Heartbreaker (twig man + wedding cake; refer to the Weapons list below if necessary)
Make Love to the Camera
Go to the "Can You Smell It?" building and walk in front of the camera by the green screen
Making a Splash
Go to Whiplash and jump into the water from the highest diving board
Om Nom Nom
Put a human in the cauldron on Voodoo island ("Masterchef" achievement)
Craft the Antiquer (flour bag + mouse trap)
Craft the Mind Controller (boombox + crystal ball)
Sister From Another Mother
Kill zombie goats
Starve (you won't be able to get this with the No Hunger mutator)
Someone Could Step in That!
Kill the zombies that spit green stuff toward you
Eat food items
Go to the hill near the Studios where there's just a chair and a bag of flour
Ride a stretcher (found behind the hospital)
Ride a stretcher (above), hit a zombie to put it on the stretcher, then deliver the zombie to a drop zone (either behind the hospital or near the Governor stand)
Take It Easy
Craft the Relaxer (vial of goo + broken minifun)
Tastes Like Chicken
Craft Edible Food (barrel + sugar; refer to the Items list below if necessary)
To the Moon!
Ride a firework (can be found at the circus, the roof of the crafting table garages, and the roof of stage 2 at Studios)
Turn it up to 11
Go to the wipeout course at Whiplash and headbutt the handle
Craft any weapon
What's for Dessert?
Eat until your hunger bar is full
Buy a window at the window shop on the second floor of the mall
You Spin Me Round
Ride the large ball at the construction yard (across the road from the goat pen)