If the muscles still look abnormally large even when relaxed, it's a pretty good indication that some synthol has been used. This Big Joe does look like he has used some, but not as much as others. The classic synthol user was probably Brad Hollibaugh. While his synthol use was very observant, it's nowhere near as bad as others like Greg Valentino (even though he denies using synthol, he says he used a different product) and Kirill Tereshin.
I'm not going to post any photos because it doesn't really fit the theme of the thread, and quite frankly, I think it is a horrendous look. If you want to look like a balloon animal, that's on you, just don't ask me to support it.