The weekend before one gets the "good" paycheck for each month. Because one can't achieve much when s/he is faced with this kind of weekend, s/he feels as if s/he were a person stuck playing baseball in right field.
It's so boring being stuck in the house with nothing to do 'cause I don't have any money to go anywhere. I just paid the rent, so it's another paycheck down the toilet. Oh, well, another right field weekend!
Plot twist! Unlike the baseball term, “out of left field”, which is way over used and now expected, the term, “out of right field” is actually unexpected.