drop by- to go somewhere for a short period of time
out front- in front of the house or building
classes are full- classes already contain the maximum number of students
back yard- area behind a house (usually an area of grass)
to lay out- in this context "laying out" means "to be laying outside in the sun"
all of the sudden- colloquial way of saying "suddenly"
to come out of nowhere- to appear suddenly
crap- in this context "crap" means "feces"
to be pissed- to be mad
to scrub- to wash by rubbing something hard
to get something out- in this context "to get something out" means "to wash something out"
stain- a mark or spot that can not be removed by washing