Standard birth control methods aren't usually effective against a Swanson

Ep. 01: London (Pt. 1): Birth Control

Ron Swanson gets some life changing news.

Diane Lewis:

“I’m pregnant.”

Ron Swanson:

“I see.”

Diane Lewis:

“I don’t understand how, we were so careful.”

Ron Swanson:

“I warned you about this. Standard birth control methods aren’t usually effective against a Swanson.”