translated

ポロリ is pretty much a warddrobe malfunction from looking it up in google and wwwjdic

and the lower right panel could also just be "Too-Much-School-Swimsuit" but i felt the context was better with the last panel

maybe not?

the lower right panel has a negative context on the school swimsuits, he wants more skin

I think he loves school swimsuit because he says "yahoo(うひょ～)" in lower right panel, so "Too-Much-School-Swimsuit" as you said or "So-Many-" is better.

His sayings "~~だらけの**大会！ポロリもあるよ！" is a set expression of Japanese web-site even if ポロリ is meaningless. There are so many sites that uses similar phrases, e.g. "ウサギだらけの餅つき大会！ポロリもあるよ！(Rice Making Meet of So Many Rabbits!)" for Eientei.