Guinness Boy - I do get that - an almost involuntary shout, just out of habit. But this bloke absolutely BELLOWS it for about ten seconds. It's a bit "look at me".
There's some bloke at the back of N1H who often shouts "SEC-OND BAAAAAAAALL..." incredibly loudly when there's an aerial challenge.
Presumably he thinks this is a 'proper' coaching phrase and therefore makes him look good. Even if players did hear shouts from the stands, it's unlikely that...