BRING BOXES!!! CARBOARD BOXES!
315 is a mental barrier. so get your buddy to load up the bar with random but increasing ammounts, using small denominations (the 5's,10's and 25's) so that you cant hear what hes putting on. and then have him put cardboard boxes over top of the weight, so you cant see them (you have to have your eyes closed the whole time). then go and bench
youll probably hit 315-325 or somethin