BEST BETS FOR MONDAY, APRIL 21, 2008

	WONDER PETS! Nickelodeon, 7 p.m. ET I wonder how many of the toddlers and young ones watching today’s installment of this visually playful children’s show will get all the fab references – fab as in Fab Four, that is. The name of the episode is “Save the Beetles,” and the titular heroes dispatch themselves to go save the mop-topped quartet – who are stranded beneath the waves in a “yellowish submarine,” stuck in the clutches of kelp. Kelp! I need somebody! Kelp! Not just anybody! Kelp! ...
	THE BIG BANG THEORY CBS, 8 p.m. ET The wait is over. The excitement is here. Yes, it’s Physics Bowl! And will the gang, in blue, defeat the opposing team, dressed in vintage Star Trek uniforms? Set punch lines to stun.
	THIS IS SPINAL TAP VH1 Classic, 8 p.m. ET On the comedy scale, this brilliant 1984 rockumentary spoof goes all the way to 11. Ron Reiner directed it, and Christopher Guest, one of the Tap stars (along with Harry Shearer and Michael McKean), played very close attention. He’s been making the same sort of freewheeling, quirky, delightful comedies ever since.
	HOW I MET YOUR MOTHER CBS, 8:30 p.m. ET Cobie Smulders, as Robin, gets to delve into her embarrassing musical past again, as another syrupy pop video from the ’90s, “Sandcastles in the Sand,” surfaces, to the delight and horror of the rest of the gang. So does an old boyfriend who co-starred in that particular video – played, with tongue firmly in cheek, by former Dawson’s Creek star James van der Beek.
	TWO AND A HALF MEN CBS, 9 p.m. ET An outraged boyfriend of one of Charlie’s sexual conquests seeks him out and punches him in the face – sparking a trend.
	MEDIUM NBC, 10 p.m. ET In tonight’s episode, Allison (Patricia Arquette) is rushed to the hospital on a stretcher when her visions get all wobbly. If she lapses into a coma, that’ll be a prime-time hat trick: Earl on My Name Is Earl and Eli on Eli Stone also were comatose in their shows’ most recent episodes.