Usually, if you access information like p.first_name, that information is now needed or necessary in the process. It has to be provided.
By wrapping this expression with SNEAKY, you prevent that behavior. Instead, the system will just skip over it.
As the more general version of the *_OF_ANY operators, SNEAKY can be very handy for complex KYC calculations.
p is Person
p.domicile = ch
This condition is true if there is a person who lives in Switzerland. However, if the person's domicile has not been provided in the case, it will not be asked for, because we wrapped the expression in SNEAKY.