@GeeKay
パンいち seems to be a contraction of パンツ一丁(pantsu ichou)
パンツ一丁 = (wearing only) a pair of underpants
尾上 = i suppose this is his name
じゃん is a contraction of じゃない = isn't it
so i think it will be something among the lines of "isn't it underpants okami?"