from Wiktionary, Creative Commons Attribution/Share-Alike License.
superlativeform of muscly: most muscly.
Sorry, no etymologies found.
If you're small you get your biggest muscliest friend to push their way through to the front and everyone follows in a chain, holding hands if that's the only way to stay together … it works but it is REALLY annoying to the people who are up front because they bothered to get there early.
The gist is this: a variety of bandits have swiped the city's supply of bulk-up powder, and it's up to the muscliest, oiliest men (and man-like bears) in town to chase them down and get it back.