For the third time this month, the 18-year-old has unveiled a new tattoo. The ink addict’s latest, which he showed off Monday, is of Roman numerals – I, IX, VII, and V – which presumably stands for 1975 … though a math teacher would wisely note that the year would technically be MCMLXXV.

So what is the significance behind 1975, which now has a permanent and prominent spot on the teen idol’s right collarbone?

Well, it turns out Bieber is a huge mama’s boy. The disco-era year is the one in which his mother, Pattie Mallette, was born. And the mother and son share a special bond – in her recent book, "Nowhere But Up: The Story of Justin Bieber's Mom,” Mallette talked about becoming pregnant at the age of 17 and opting not to abort the baby, despite being encouraged to do so.