If this sounds strange, it's because it is. In 1973, Yankee pitchers Fritz Peterson and Mike Kekich called a press conference where they announced that they had traded families. The men were going to swap wives, children and even pets.
The two men had been inseparable since 1969, and the families had spent a lot of time together. One time, during a double date, they joked about wife-swapping. According to the report, the swap occurred during the summer of 1972, and then made the change official in October of that year, and they made their press conference the year after.
The trade ended up working better for Peterson, because he's still married to his swapped wife, and had 4 kids. Kekich divorced soon after.