The Colour of Alphabets

I was trying to play with the kids a little game of name the colour which starts with the said alphabet
A? - red (I said, correct- apple red)
B?- yellow-
I said - no B is blue, brown, burgundy, beize
They insisted- no B for yellow
I gave up- ok its also blue, brown....
C for - blue???
D- green...
this went on and on with the colours blue, green, red and yellow being alternated.
Until we reached some P that I realized they were telling the colour of their Alphabet blocks!