It's just a type of reverb effect. My friend had a reverb pedal and that particular effect could be emulated on it... dunno about any specific fx pedals to buy, though, he was using a BOSS something.
- He who observed it served it.
- He who first detected it ejected it.
- He who said the rhyme did the crime.
- Whoever blamed it flamed it.
- Whoever spoke last set off the blast.
- Whoever rhymed it grimed it.
- Whoever denied it supplied it.
- He who smelt it dealt it.
- The next person who speaks is the person who reeks