i don't know what it's called, but there's a bodyweight tricep exercise that's killer. grab a bar that's maybe a little higher than waist height, bend forward slightly, lower myself down, then push myself back up. i don't know if that's good enough explanation. but it kills my triceps. go on to youtube, go onto the f0rtress' channel. look at his video "get big triceps with bodyweight exercises" or something like that. he has massive arms and everything, all from calisthenics. his triceps are massive!