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 remember
7. you don't look them in the eye
8. you get away with it
9. she says it's ok
10. you can please all of them
11. you go home afterwards and fulfill your duty.
12. you're in a different area code, not to mention a different state.
13. you have two girls at the same time, so one invalidates the other.
14. it was actually them but you were thinking of someone else
15. it's with royalty
16. It's in a different ZIP code
17. you get paid
18. she's not human.
19. you change the sheets afterwards.
20. they're on top