Yes, I loved those singing trashcans in the 'Vegas'-episode too! I completely agree with Alex here: strangely enough, those absurd bits, like Dewey's hamster practice ball rolling through scenes in various episodes, Hal's daydreams etc, didn't make the series less realistic. It's over the top, yes, but I still recognize so many bits from my childhood and from my friends'. Balancing the craziness with the realism is a tightrope act, but the way they managed it was pure genius!
There are so many comedy shows out there that are just lame (especially in the acting: often, actors, especially in American routine shows, seem to be more sleepwalking all the way to the bank than acting), neither realistic enough, nor fanciful, or original, and this one hits all the right buttons.
Yes, I loved the bit from 'Hal Quits' too: Malcolm dreaming about his boring jobs, imagining a busload of his alter egos (that's throwaway genius, a brilliant CGI scene that is gone in the blink of an eye!) and then waking up when a cross-dressed Malcolm welcomes him as his wife and kisses him!
Rich