5 perhaps being the number of strings on the bass? (I haven't seen his bass, but I know the guitarists use 7-strings, so it's only natural the bass player would use a 5-string)
Then there's this band called Slice The Cake...

Bunch of faggots putting random riffs together and calling it "progressive" deathcore.
Stupid name.
Probably picked "for teh lulz"

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