Use this...
I'm sorry, if something happened to it while I were holding it, it would be my responsibility, and I'm not comfortable with that. Have your friend call the store please, at this number.
I actually use something along these line with specialty cakes at the store, because I did almost drop one. This does not make people happy, especially when I refuse to pick up their giant sheet cake out of a cart so I can ring it up, but I am also not going to be responsible for dropping said cake.