To start, everyone picks a different number. You should probably pick a small integer. For this example, i will choose "5".
The game begins when everyone is ready, and the SecurID generates a new code.
You then attempt to combine all six digits generated by the SecurID in any mathematical fashion (add, subtract, multiply, divide, powers, parentheses, combining-digits etc) to result in your previously chosen number. When you come up with an answer, tell it to everyone. In this example, the SecurID says "312181", so I would say "(8+1)/3+2^1^1 = 5".
If you cannot come up with an answer by the time the SecurID generates a new code, you drink.
Repeat as needed.
[*] RSA has nothing to do with this game... except for manufacturing the equipment!
[**] Variation for the mathematically inept: you can use any but not necessarily all of the six digits.