Your friend would be better opening a vanguard account and setting up a pension or isa. He can invest in the UK or US markets via a tracker fund at very low cost. The pension option is especially attractive atm since he's buying near the bottom of the market and getting 25% tax relief - that's £250 free for every £1,000 he puts in.
If he wants to outsmart the market though he'd be better off saving his cash and using it instead of loo roll.