Hi guys,

I have this girl (coworker) and I asked her out on a lunch last Friday via email (as she works at home on that day) and she said yes but called in sick today (Monday).

She also said once she will buy a gift for me and asked me what I want

This girl rarely calls in sick.


What could be the reason?
Is this a sure sign that she is disinterested?

What should I do tomorrow?

She is a 9 but she is also your coworker. Be carefull, it's kind of social circle game!
Go out for lunch with a coworker is something normal, you don't need a lot of compliance from your coworkers to do that. Not a big IOI.
So keep it casual, don't look interested in her (active disinterest) but DHV!
Do what you normally do when you lunch with a Bro.
During the conversation, try to know how is her relationship with her BF.

Cool man. Do you think there's an IOI from her?

I have to say "no" to not fool you...
You know have lunch with coworkers is something normal, it don't need a big level of compliance. Maybe she already done that with others coworkers, males or females.
In example, i'm a medical student and i'm naturally friendly. If I ask to every HB9 I know in my class if she is interested in having lunch with me, i'm pretty sure to have a high level of positive response because i don't ask her to kiss me or date me, just have lunch...

It's a lunch, not a date: you lunch with bros, family, coworkers,... It's being social.
Assume that it's not a IOI, continue DHV and active disinterest.

Hey mate she now told me she was sick and she now asked me to go for lunch tomorrow.

Say "OKAY. Tomorrow it is." But make your intent known. Don't do this Mystery Method HORSESHIT unless its congruent to you being an asshole / playing hard to get. Personally, I see no need for it.

Hey I was gonna to ESP, 5 question game and then Cube at the end. Of course they will be mixed in during conversation about relationships in general and some NLP. Is this a good plan?

Also. Do I pay for lunch or dutch?

Any advice would be appreciated guys...