You are agreeing to make the payments if the borrower does not. But, the borrower is your friend and he would never do that to you, right…?
… Maybe. Not on purpose, but if he’s not very good with money, or has money troubles, it could “just happen.”
A lender only asks for a co-signer if the borrower isn’t creditworthy on his own. The lender could have good reason if your friend has a poor credit history, or doesn’t make enough money for a loan of that size. Or, it could simply be that the lender has no proof that your friend is good with money, because your friend has never taken out a loan or had a credit card before.
Because they are unsure about your friend, they’re counting on you to step up and take responsibility if things go badly.
Remember, if your friend doesn’t make the payments in a timely manner, or doesn’t make them at all, it will show up on YOUR credit history as well as his, and hurt your credit score.
If your friend is too embarrassed, or too disorganized, to tell you that he hasn’t been paying the loan, you might have to make a really big payment to get the loan current again.
And by then, the damage to your credit score will already be done. It will take years for the late payment history to drop off your report.
I know you want to help your friends, but, think carefully before you make a decision that could change your finances for the worse.