I worked at a place for literally 4 hours, and got a 40$ paycheck, do I need to file that as income?

[jcurl5408]

Yes. This is still income you earned.

[hbl3973]

You do include this in your total income.  The question of whether to file taxes depends upon your income level, filing status, and whether you are someone's dependent.  See IRS publication 17 (https://www.irs.gov/pub/irs-pdf/p17.pdf) starting on page 4 to determine if you have to file.  Even if you don't have to file, it may be to your benefit to file to, for example, get a refund of income taxes withheld from your pay.