PENNY TRIES TO THROW A WRENCH INTO LEONARD'S PLAN TO BE A SPERM DONOR FOR HER EX-BOYFRIEND, ON "THE BIG BANG THEORY," THURSDAY, FEB. 7

Keith Carradine Returns as Penny's Father, Wyatt

"The Donation Oscillation" - Penny tries to seduce an abstaining Leonard to ruin his "donation" for her ex-boyfriend, Zack (Brian Thomas Smith)
, and his wife, Marissa (Lindsey Kraft)
. Also, Wolowitz, Bernadette, Anu (Rati Gupta)
and Koothrappali turn Koothrappali's canceled bachelor party into a couple's trip aboard the "vomit comet," on THE BIG BANG THEORY, Thursday, Feb. 7 (8:00-8:31 PM, ET/PT) on the CBS Television Network. Keith Carradine returns as Penny's father, Wyatt.

REGULAR CAST:

Johnny Galecki (Leonard)
Jim Parsons (Sheldon)
Kaley Cuoco (Penny)
Simon Helberg (Wolowitz)
Kunal Nayyar (Koothrappali)
Mayim Bialik (Amy)
Melissa Rauch (Bernadette)

RECURRING CAST:

Keith Carradine (Wyatt)
Brian Thomas Smith (Zack)
Rati Gupta (Anu)
Lindsey Kraft (Marissa)

GUEST CAST:

Eric Nenniger (Neil)

STORY BY: Bill Prady, Jeremy Howe, Adam Faberman

TELEPLAY BY: Steve Holland, Dave Goetsch, Maria Ferrari

DIRECTED BY: Mark Cendrowski