The Piggy Bank.
The Piggy Bank is a premium mechanic in Egg, Inc.
Mechanics
The Piggy Bank increments by a number of Golden Eggs every time something is upgraded or purchased.
You can crack it for US$4.99 or £4.99 each time, which will reset the counter to 0 and give you all the Golden Eggs inside. Contract goals and the Daily Gift Calendar may also add Golden Eggs to the piggy bank and even double it.
Bonuses
Each time the piggy bank is cracked it gains a bonus, starting at 2% on the first level, 25% on the second level, and .10n+.10% after that point (e.g. level 6 would have a 70% bonus). Sometimes, Special Events will put the piggy on sale.
Piggy Cap
At a certain point, the Piggy Bank fills up and cannot be incremented by buying things. This is a soft cap, though, and the Piggy Bank can still be increased with contract or Daily Gift Calendar rewards.
- Prior to level 5, the cap is
10,000n, where n is piggy level. - At level 5 and up, the cap is 50,000+5,000n, where n is piggy level.
Strategy
Note: There are 10 levels. The strategies below only apply to people who are willing to spend real-world money to crack the piggy. If you're certain that you'll stay free-to-play, feel free to ignore this.
Ever since the cap was implemented, it became effortless to max out a Piggy Bank. However, strategies may still be applied. For example, the piggy should be close to maxed when a 
x2 is expected to get the maximum reward from it.
Keep in mind that you need 
1,813,662 to get all Epic Research plus the Hyperloop.
You may wanna buy this over the other offers, as this is the cheapest way to get golden eggs while still paying for them.
Trivia
The piggy bank used to cost $2.99 and £2.99, but it was changed on 14 July 2019 after the $1 piggy sale.
Gallery
