Can underaged people get into a rated r movie if they have a printed fandango sheet?

No for two reasons, fandango tickets require the credit card used to purchase the tickets to be presented at the time of entry. So basically, if you don't have the credit card used to buy the tickets, you can't use the tickets. Most credit cards don't allow minors to possess them (of course there are exceptions). The other reason no, is because they WILL still ask for ID if you look to young. BUT... If you don't look young, this may be your best shot.