Instead of playing a synth, just make your shorts-wearing lurch of a bass player do it, right? You can get synth-like square wave tones via the oscillator on settings 1-7, or the other modes cover some varying auto-wah type stuff. Heaps of fun, sounds killer. 

Model: Boss SYB-3 Bass Synthesizer
Made: Taiwan, May 2000 (serial AN46926)
Type: synthesizer/filter
Power: standard 9v negative supply or battery (not included)
Equivalent new street price (approx): n/a
Mods: none
Accessories: no box or docs
Condition notes: used, few marks/chips etc, good condition