kalajan is incorrectly written, and should be written as "Callaghan" being its meaning: It is a way to deform the surname of English origin Callaghan. It is a term or name used in pseudonyms or nicknames.
Kalajan is a nickname used on the internet without having a particular meaning, could well say that people who use kalajan as mote or nick are vigorous, very entrepreneurial people and that they don't stop at nothing or to anyone.