But the joke is: is absurdly tacked onto a very casual, domestic Japanese sentence — as if “being huge” is an official, checked fact.
As for the "verified" part of your search query, it seems you might be looking for information on the series' authenticity or legitimacy. Rest assured that "Uchi no Otouto Maji de Dekain" is a genuine manga and anime series, created by Rin Kokumai and published by various Japanese media outlets. uchi no otouto maji de dekain verified