at the college office anna's mother you will have to do this before you bring anna home it can easily be skipped by mistake it will trigger when you are at the right time and at the place in the game if you did bring anna home already then you have to edit your save file or use the console by pressing shift+o but you will have to edit file to enable it you have look for 00console.rpy open it with any text editor and look for config.console = False and change it to config.console = True then load the game then press shift+o then type in $ dean_trap = 1 then enter then type exit to close the console
location of where the file is located
D:\DOWNLOAD\DON'T DELETE\My_cute_roommate-1.6.01ex_BETA-win\My_cute_roommate-1.6.01ex_BETA-win\renpy\common