I have no idea what 50 Shades of Gray is (living under a rock is nice and peaceful)
I tried to think of the most appropriate way to tell you what 50 Shades of Grey is, but I couldn't come up with the best words to use, aside from telling you its a series of books. So, instead, I'll let amazon describe it to you, in case you were wondering..
"When literature student Anastasia Steele goes to interview young entrepreneur Christian Grey, she encounters a man who is beautiful, brilliant, and intimidating. The unworldly, innocent Ana is startled to realize she wants this man and, despite his enigmatic reserve, finds she is desperate to get close to him. Unable to resist Ana’s quiet beauty, wit, and independent spirit, Grey admits he wants her, too—but on his own terms.
Shocked yet thrilled by Grey’s singular erotic tastes, Ana hesitates. For all the trappings of success—his multinational businesses, his vast wealth, his loving family—Grey is a man tormented by demons and consumed by the need to control. When the couple embarks on a daring, passionately physical affair, Ana discovers Christian Grey’s secrets and explores her own dark desires.
Erotic, amusing, and deeply moving, the Fifty Shades Trilogy is a tale that will obsess you, possess you, and stay with you forever.
This book is intended for mature audiences."
Hopefully he's not too embarrassed when he finally figures out what he gave his Grandma