A word for the oppisite of forgetful?

ok so me & my friends are making homecoming shirts,
and putting a little sarcastic nickname on the back,
and we want it to have the word one on the end,
like for example one of my friends is really short,
so his is,
the tall one.

well we need a word for the oppisite of forgetful, air headed, etc.
dont worry, im not being mean to my friends, this nickname is for me,
cuz i'll admit, i can be a little air-headed sometimes, lol

so we need a nickname.please help =]
how about "mindful" or "retentive"