1. they look similar. then it's just a tribute.
2. it's with a celebrity
3. they're twins
4. it's a threesome
5. you spread peanut butter on your balls and your dog licks it off
6. you don't look them in the eye
7. you don't remember
8. you get away with it
9. she says it's ok
10. you can please all of them
11. you're in a different area code, not to mention a different state.
12. you go home afterwards and fulfill your duty.
13. it was actually them but you were thinking of someone else
14. it's with royalty
15. you have two girls at the same time, so one invalidates the other.
16. you get paid
17. It's in a different ZIP code
18. she's not human.
19. you change the sheets afterwards.
20. it's with their best friend