老家伙 ;老伙计 like old buddy;old pal~;hey man ~ ...sth like this... ^^

Can be derogatory as well. All depends on the tones it was said. At the same time, it can mean an old foreigner (non Chinese)

may i know if your family name sounds like gui? if not , that is only a nicky name . Your need to ask the one who give you this name , only him knows how to explain the meaning .

Min-ga-la-bay khamya: okay, your statement sounds good, it could may specialist terms of word in your groups. well, by the way you say, the tone (lao4 gui2) isn't match lao2-gui3(老鬼）,which is has negative meaning. but, i would like you to ask them how to write them letter, i also wonder to know how it write. Da-Da, G-zu-ting -ba-day!

老鬼（laogui) is a strong word, that use for looking down someone, and unrespectful to the others ,and it is kinda cursing words becuz of the anger, and dont like someone, etc etc etc. unless if your family name is sounds close to "GUI" or else i dont see any positive meaning of this word (Lao gui) the guy who called you in that way is very RUDE to you, and no respectful at all. !!!