Something like "オッ would also be acceptable". As in, both デカ and オッ are suitable replacements for the ○○. It's hard to get across the joke either way, really, with the parenthesized part or without it. You'd have to figure out some kind of pun that somehow fits all three meanings. Got anything in mind?
Oh I know Getsuyoubi no Tawawa, with anime I meant Spy x Family. (Specifically, why is Volley-bu-chan trembling...)
The joke is entirely in the title. Spy x Family is スパイファミリー in Japanese. The post blocks out the first letter with two circles and suggests those circles could be filled with two other alternatives, yielding either デカパイファミリー ("Huge Tits Family") or simply オッパイファミリー ("Tits Family").