S1·E13 The Unsinkable Mommy Adler

Grace's visiting mom, Bobbi Adler, a would-be star whose propensity for breaking out into show tunes and impressions dismays her daughter – and delights Will, Jack and Karen – wreaks havoc by suggesting Will and Grace wed, despite their sexual differences. When Will winces at the fantasy of committing to anyone who needs to be the star of a relationship, Grace realizes she's more of a chip off the old block than she imagined.