So when they call back the second time you have 3 choices:

1. Say just a minute, i'll go get him/her. Then you lay the phone on the counter and walk away.

OR....

2. When they ask for Joe whoever, say I'm sorry he can't come to the phone right now..... he's fucking my wife.... then hang up.
If they ask for Susie whoever, say gee she can't talk right now, she's got my cock in her mouth..... hang up.

OR.....

3. My favorite whoever they ask for say, awwww you just missed him/her. But i'll tell him/her you called..... hang up.