Han Solo. You mack. The only lady I could get away with saying, "I know" in response to "I love you" to is my mama. I actually have proof of this in the form of the one other time I tried it on the one other lady who ever told me she loved me. I got a Hi-C juice box thrown at me, and it hit me in the gut. It hurt too, dude. We were in 7th grade at the time, but "I love you" ended up being a star pitcher on the girls' softball team when we got to high school. I think she even went to college on a scholarship for that arm. I also think she grew up to be a lesbian, so I bet in retrospect she is glad I pulled out my slick Han swagger and didn't "I love you" her back.
Anyway, here are some nice pillowcases with the famous Princess Leia/Han Solo "I love you," "I know" quotes from The Empire Strikes Back. I like them because I think women will find them cute and acceptable as gifts, but they still make men seem cool and in control of their lives, rather than like the whipped little Bs they probably are by the time they reach a point in their relationships that they're buying His & Her pillowcases.