Apparently paraskavedekatriaphobia is more relevant than triskaidekaphobic. However @barkingmonkey considers friggatriskaidekaphobia slightly masturbatory... (according to Stephen Fry).
Now, who knows what they mean?
triskaidekaphobic - fear or a phobia concerning the number 13
paraskavedekatriaphobia - fear of Friday the 13th
friggatriskaidekaphobia - A morbid, irrational fear of Friday the 13th. (The link for this one actually has a bit of info why it's called friggatriskaidekaphobia as well)
If you want to go look those up on google youself then go ahead!
By the way, Hippopotomonstrosesquippedaliophobia means fear of long words!
The Phobia List