Bread is slang for money. When bread is being baked, the yeast creates little air pockets—hence “bubble”— which makes the bread expand. In this case, money is expanding/growing.
Now you double up, time to bubble up the bread and huddle up
Bread slathered in mayonnaise then fried in bread crumbs served warm and guaranteed to give you a stomach ache however, some brace few find it delicious.
Gabe: I love bubble bread
Cecilia: ew I have a stomach ache because of it.