I'm not usually a fan of Craig Ferguson but he plays very well with Robin. The bit around the beginning with the rapidfire voices/accents is a more cartooney version of interactions between me, my housemate (NeJi) and my neighbor (likely NeTi). When we hang out it's a lot of that similar playing off each other.
Seeing the way Robin riffs and ends up pulling out "two vampires in rehab" reminds me of an interaction between my and my housemate when our third housemate's girlfriend made too much rice and we ended up riffing all kinds of things until we very seriously were discussing how one could best sculpt a bust of their face out of rice.