The term bottle- lo comes from when in the 60's empty beer bottles were recycled and collected by a bottle collector hence the term. He was called a the "bottle-lo"
Because "thank you" is difficult for very young children to say, so they are taught to say "ta" because it is easier for them until they can actually say "thank" you. The "slab" of beer, is reference to the carton of beer looking like concrete slab.