Kaley Cuoco surprises her mom with a brand new Lexus on Dec. 23, 2013. Credit: AKM-GSI (2)

Big Bang Bucks! Just a few days before Christmas, Kaley Cuoco surprised her mom, Layne Ann Cuoco, with a present too large to fit under the average tree. The Big Bang Theory star, 28, bought her mom a brand new dark blue Lexus RX350 -- unveiling the present on Monday, Dec. 23 outside of her house in Los Angeles. 

Photographers captured the precious moment when Kaley bestowed the generous gift, and Layne's shocked face says it all. Nearby was Kaley's father Gary Cuoco and younger sister Briana Cuoco, who recently appeared on season 5 of The Voice

Cuoco's fiancé Ryan Sweeting was also close by. As previously revealed by Us Weekly, the couple of six months is set to tie the knot on New Year's Eve in a fire-and-ice-themed holiday bash featuring plenty of cocktails and dancing. 

They recently had a pre-wedding vacation in the Bahamas and documented the romantic getaway for all of Cuoco's Instagram followers to see. Cuoco and tennis pro Sweeting, 26, got engaged in September after just three months of dating. 

"I know that it seems a little crazy on paper," she told ET after Sweeting proposed. "But it's what works for us."