A holiday (sometime in the middle of summer) made up by a retail store to increase sales during the summer slump.
Homer: Happy Love Day!
Lisa: It´s just a holiday that the stores made up to make more money
Homer: I´m not gonna have you ruin another Love Day.
A holiday made up by the retail stores just so they could boost sales during an otherwise slow part of the year where sales are down.
"We made a huge splash last year with Christmas 2"