Dak Prescott's offseason just keeps getting better and better ...
Just weeks after the NFL star inked a MASSIVE 4-year, $160 MIL contract with the Dallas Cowboys ... he bro'd down with 2 country music stars on an epic fishing trip in Louisiana!
The 27-year-old joined up with Jimmie Allen and Chris Young, as well his brother Tad and his Cowboys teammate La'el Collins, for the adventure ... and it looked fun as hell!
Allen -- whose "Best Shot" tune is STILL crushing it on country music radio -- documented the trip on his IG .