Explosive - slug fest is a play on English words. "Fest" is an older spelling of "feast", i.e. party or celebration.

Slug has many meanings in English, two of which are as follows:

"Slug" can mean to hit someone really hard. A slug fest is a like a bar room fight, with many people involved.

A "slug" is also a type of worm (?), gnerally found under rocks or in damp places, that moves very slowly (similar to a snail, but no shell). So a slug fest is a "party" amongst very slowly moving creatures...

Thus ends the English lesson for today...

BW