Thumper is the name of one of two women acting as guards for Blofeld to prevent anyone from seeing the reclusive Willard Whyte. The character were developed especially for the 1971 film Diamonds Are Forever and was portrayed by Trina Parks.
When James Bond enters the house where Mr. Whyte is supposed to be staying at, he's greeted by these two beautiful women, who quickly attack him using various athletic jumps and kicks. James Bond is even choked by Bambi's thighs, but soon gets out from that predicament, only to be thrown into an outdoor pool. Sensing an opportunity to finish Bond off, the two women dive in to the pool and attempt to drown him.
The exhausted and beaten Bond looks to be easy prey for these nimble karate experts and they quickly seize the advantage and hold Bond's head underwater. However, it soon turns out to be a tactical error for the ladies. Transferring the fight to the deep end of the pool, negates their martial arts skills and Bond is quickly able to turn the tables on the girls and holds them both underwater until Felix Leiter and his men show up. Bond continues to hold the ladies underwater for 30 seconds as they thrash about. By now their struggle indicates that they are desperate for air.
Bond lifts their heads up for a quick breath but then it's right back under immediately while he talks amusedly to Leiter, who complains about Bond wasting time in the pool. The bubbles and struggles of the women underwater indicate that they are near drowning at this point and Bond senses that they might be ready to talk. Bond first releases Thumper, and she desperately uses her last breath to swim to the poolside while Bond continues to hold Bambi under. Thumper knows that her partner needs air so she complies by pointing to the shed below where Whyte is being held. Then Bond releases his hold on Bambi, who desperately swims to the side. Bond, heading for Whyte, leaves behind the exhaustedly coughing women who are holding on to the sides of the pool, gasping for air before they are presumably arrested.