You're going to need more money buddy! A lousy 20 isn't going to cut it. Not even at the cheapest roach restaurant or greasy spoon restaurant.
Where can you go feast for $20? Wife and I used to go to Wendy's for their "5 for $5" special once a month; now it's a four for four deal; but we always swap the fries for chili so not a bad trade.
In the OP’s second comment he referred to taking his wife. My reply was for two people. A Big Mac is over $5, fries you can add another $2 and a drink will be $3. If you add in a dessert, ice cream or cookies and don’t forget tax, for two people it’s going to cost you more than $20.00. On rare occasions my wife and I will go to McDonald’s for dinner and we usually spend $22-$24.