A witty play on the phrase bel canto. The construction is a spoonerism that refers to one's ability to belt out a tune. Has been used as a self-deprecating show of modesty by a performer who was being showered with praise. Could be used by a critic to express the opinion that a singer's skills aren't as advertised or if the performer's ego is an issue.

ex.: "My singing is more can belto than bel canto"