example.cs

var exceptionTrappingLazy = new Lazy(() => CallExternalService());

try{
    // Accessing the Value property will execute CallExternalSe4rvice()
    // Now, imagine that the external service is down
    // The call to CallExternalService() throws an exception
    var lazyValue = exceptionTrappingLazy.Value;
}
catch {...}

try
{
    //Accesing the Value property again won't call CallExternalService()
    //It will throw the trapped exception again!
    var lazyValueAgain = exceptionTrappingLazy.Value;
}
catch{...}