Use a ball ... weight it first, then determine it's volume, and divide mass by volume. Weigh your empty cup, then add your viscous material (which should have been measured for volume in a measuring cup)and weigh it again. Subtract the weight of the cup to get an accurate weight of your liquid. Mark your cup at the level the liquid meets. Place the ball on top of the liquid and use a stopwatch to time how long it takes to reach the bottom (velocity).
Equation: Viscosity = (2 x (ball density - liquid density) x g x a^2) / (9 x v) (where): g = acceleration due to gravity = 9.8 m/s^2 a = radius of ball bearing v = velocity of ball bearing through liquid
If you want to compare the viscosity of 2 liquids you can do it by applying the same number of drops of both to the top of a clean piece of glass that is horizontal (i.e. laying flat). Then tilt the glass to an angle of 45 degrees, the one with less viscosity will flow to the bottom of the glass faster.