A quick puzzle (Day 1)- What am I? [closed]

You can give me anything, I will shrink it and hand it back.

Give it to me again, and I will return it to full size

What am I?

closed as too broad by JMP, Gamow, Engineer Toast, Beastly Gerbil, Mike EarnestAug 16 '16 at 16:07

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• ANSWER ACCEPTED, though if you have other ideas as an answer, go ahead! – Dan Brown Aug 15 '16 at 19:55
• Riddles should have one answer. If they have more than one equally valid answer, they are too broad and should be closed. – Deusovi Aug 15 '16 at 20:12
• Also, please check tag wikis before using them - this is not a [logical-deduction] puzzle. – Deusovi Aug 15 '16 at 20:12
• @Deusovi I'll check now. Also, they are not equally valid, just alternatives no-one thinks of. – Dan Brown Aug 15 '16 at 20:20
• The validity of an answer does not depend on how many people think of that answer. The usual "just because you didn't think of it doesn't mean no one will" word of advice also applies here. A "less valid" answer to a riddle would be something like an answer that requires a leap in logic or an answer that doesn't doesn't fully fit the clues. – Dennis Meng Aug 16 '16 at 3:32

Could it be

A zipping program (winzip, winrar, etc)

Reason is pretty self explanatory.

Zipping files reduces size, the program will also unzip which brings it back to its original size.

• I was going for compression, but meh, close enough. The quick puzzles are better, I think; they allow even the nubs to have a good go. I'll mark it ASAP. – Dan Brown Aug 15 '16 at 19:50

Shrinking and Growing Head Illusion

The reason:

The illusion is supposed to make the mind think an object is either growing or shrinking based off of a spiraling circle.

• Inventive, I will give you that. Not what I was looking for, but meh, illusions. – Dan Brown Aug 15 '16 at 20:27

It could be

the inverse operation, $\large1/\underline~$;  i.e., the function $f(x)=\large\frac1x$.

$\color{black}{\text{If you give it }}\text{a number > 1, }$ $\color{black}{\text{it will “hand” you }}$ $\text{the inverse of that number, }$ $\text{which}$ $\text{will}$ $\text{be < 1 (and > 0).}$   $\color{black}{\text{Submit that }}\text{value to the function}$ $\color{black}{\text{again, }}$ $\color{black}{\text{and}}$ $\color{black}{\text{it}}$ $\color{black}{\text{will}}$ $\color{black}{\text{return}}$ $\color{black}{\text{the}}$ $\color{black}{\text{original}}$ $\text{number.}$

The argument can be made that this technically doesn't satisfy the terms of the question, because you (obviously) can't give it just anything.  There are some things that you can give it that will cause it to give you a larger thing.  But that's true for the accepted answer, too, and I'd be interested in seeing an answer that does literally answer the question.

• Hmmm. I see where you are coming from. Well, If we see something like that, you can say 'I told you so" :) – Dan Brown Aug 16 '16 at 8:35