Was the character 蹦 (in 蹦极 "bungee jumping") designed to look like people bungee jumping?
That's a cute mnemonic, but not how characters work.


「蹦」does not specifically mean bungee jumping, it just means hopping/jumping/skipping, e.g. 蹦蹦跳跳 (skippity-skip).
Identify clearly what each component does in a character, and don't recursively decompose characters.「蹦」only contains two components:


Semantic component「足」(foot > actions to do with feet/legs)
Phonetic component「崩」bēng  


Don't recursively decompose this into「山」and「朋」! These don't contribute anything direct to「蹦」.
「崩」bēng doesn't contribute anything apart from sound. If you must know the composition of「崩」, its meaning is to collapse, metaphorically hinted with「山」(a mountain collapsing), and its phonetic part is「朋」péng.






Sadly, there are no friends and no mountains, but happily no collapsing in「蹦」. Stay safe!