The probability of KOT

4chan ID can contain the following characters: A-Z, a-z, 0-9, +, /
That makes it a 64 characters alphabet.
Only 8 of them are chosen in any order with repetitions.

We are looking for the following combinations of 3 characters:
>k or K
>o or O or 0
>t or T

That makes 12 possible combinations.
Since we are looking for a 3 character word, we only need to consider the first 8-3+1=6 positions.

It follows that (8-3+1) * 64^(3-8) out of total 64^8 combinations would contain the string. Therefore, the probability is:
p = [6 * 64^(3-8)] / 64^8 = 6 * 64^-5 = 6/64^5
Since we are looking for 12 possible combinations, and not just one, then it's 12 times more likely to happen
(6/64^5) * 12 * 100 = 0.0000067%

If you expand it to
>k or K or c or C
>o or O or 0
>t or T or 7

You'd get 36 possible combinations.
Which would make it:
(6/64^5) * 36 * 100 = 0.00002%

If you expand it to
>k or K or c or C
>+ or /
>o or O or 0
>+ or /
>t or T or 7

You'd get 288 combinations, but it is now a 5 character word.
Which narrows our selection to (8-5+1) * 64^(5-8)
p = [4 * 64^(5-8)] / 64^8 = 4 * 64^-3 = 4/64^3
And with 288 combinations it would be:
4/64^3 * 288 * 100 = 0.43%

And if you combine that and the previous 3 character combination, you'd get:
4/64^3 * 324 * 100 = 0.49%

The chance to get a kot id is 0.49% and watch me getting it.