There is a misconception that we nerds don't have any form of relationship with girls. So let's make fun of it. Rules are the same as the 9001 signs you're addicted to calcs and Omni.
No idea right now so I'll let someone else start the party up.

Edit : well, actually...
1 : You prefer to spend an afternoon playing Minecraft than going to the cinema w/ your gf (true story).
2 : If you had to choose between saving your gf and your calc, the choice would be pretty quick : the calc.

3. You are always too embarrassed to even talk to a girl you crush on.

4. You prefer dating other guys over girls, in which case the girls don't stand a chance with you either
5. Girls would rather take their calculator to prom than take you

6. When you go on a first date with a girl, you take your calculator to show off your latest coding achievements.
7. You decide whether or not to date a girl based on what brand of graphing calculator she uses/used in school.

9. Your girlfriend finds you in bed with someone else. Only it's not someone else. It's something else. It's your TI-84+CSE.

Hehe nice ones.
Also, Catastropher is here.

12. You are a walrus so you can't date human girls.

14. Your idea of giving a massage is running a garbage collect on your calculator.
15. When you date a girl who has the same name as a previous girlfriend, you refer to her as "version 2.0".