Friends, family and fools come first as a source of borrowing.
Then perhaps a credit card (0% intro APR if possible; that should play well against your 5 month plan to repay).
LendingClub, Prosper.com, and similar make a song and dance a possible vector for getting crowdsourced loans.
Then perhaps a bank loan, or title loan/second mortgage if you have anything of value.
Depending on what you plan on spending the money on, store credit cards from Walmart, etc. can also come in handy.
Hopefully you're not planning on investing it in Bitcoin mining equipment from a mysterious seller on the internet.