Choice of splendour
Cousins who used to love each other grt married seperately,.
Similar to "Yo, DJ". Bo in this case is a salutation and/or interjection and "selector" is a name for someone who "selects" which records to play - like a DJ.
Can also be used as a celebration.
or as an expression of grief.
"Bo-Selector! Spin some phat tunes man."
"Bo-Selector! I've just won the 1st prize at the WI raffle!"
"awww, bo-selector, that was my last 50 pence"