A LOT of cum
Normaly the result of a huge gangbang
where the partisipants all cum in a bucket. This is sometimes followed by pouring it on someones head.
The alturnative meaning is after a party a poool of white mess is left on the floor/bed/sofa/bathroom floor.
AL:Do you think he will ever get that stuff out of his hair?
LIAM:No! It was like a sea of white.
AL: What a night! But we have to get this place cleened up. I don't want my olds
comeing home to a sea of white.