What kind of frog is that

[mamangenn]

It was yellow when my friend received it and the next morning was brown

 

[AfroNewtkeeper]

That would be a Golden Tree Frog. They change color according to their temperature, varying from a bright gold to a mottled brown, like you can see in your pictures. Make sure you guys do a good amount of research on his care. (They're also called Asian Flying Frogs, so watch out.)
Here's a few care sheets:
http://www.frogshot.co.uk/assets/downloads/Polypedates-leucomystax-husbandry.pdf
http://www.amphibiancare.com/frogs/caresheets/goldentreefrog.html
http://blogs.thatpetplace.com/thatr...ian-flying-frog-golden-treefrog/#.UwbfDIXzu-Y