Pour half a pint of lager (preferably something strong, but with a light taste. Avoid malty lagers) into a pint glass. Add a double vodka, Smirnoff works best as it's the same taste as in the Smirnoff Ice. Then finally top up with a 275ml bottle of Smirnoff Ice.
This tastes exactly the same as a Turbo Shandy, but racks in at 8.5%ABV instead of 5%.
Lethal, but innocuous.
More info on how to make a Power Shandy