Gunnar's prank for his teammates is going to be the prank of making them believe that there is a prank all day. He is going to bake them delicious baked goods for breakfast and everyone will think that there's something wrong with them, but in reality they will be perfectly baked and delicious. He will offer to put away equipment for them, and everyone will turn him down because they think he's going to do something to their stuff. He will offer them rides to and from practice, and they will probably say "no thanks" because they are sure he's going to drive them off somewhere and leave them stranded. He will invite them all over for dinner and they will be afraid to accept because they'll think he has some giant prank planned. And then at 11:59PM he is going to text the team group chat and tell them that there never was a prank, and the real prank was all the stuff they missed out on because they were too busy worrying about a prank.