"Laddie" is a word used to affectionately refer to a young boy or a young man, kind of like calling them "little buddy" or "youngster." Full definition
T330P OF THE MORNING TO YA LADDIES Hey, Im Viper Im 14 years of age and I have spent almost all of it indoors, I love anime especially studio ghibli. (petesgrillandpizza.com)
January and February are clearly long, dreary months when the little laddie can't recognise sunlight anymore. (sarahbessey.com)
If not from Krazy George, the manic cheerleader at the San Jose Earthquakes soccer games, then from old George Clark, a wizened Scot who lives in Aberdeenshire and calls Oldfield «my giant laddie.» (si.com)