This XKCD is For Sig.

9/11 was Lisa's 20th birthday.  If I remembered to offer the customary "Happy Birthday" greeting, it wan't until late in the day, after some of the shock had worn off, I'd regained my senses, and slid back into my life.  I may have forgotten that year, but there's been no excuse ever since.  She and I have the inescapable, in-your-face, patriotic birthdays: September 11th, 4th of July.  So, in that vein...

 HAPPY BIRTHDAY, LISA!