Sheldon taught Penny how to sing "Soft Kitty" because he wanted Penny to sing it to him while she was rubbing his chest.
"soft kitty warm kitty little bulofur"
"happy kitty sleepy kitty pur pur pur"
Penny really didn't want to sing but she can't refuse Sheldon's asking. So she sang it, but very unwillingly.
At the same time, Leonard, Howard and Raj used detecting machine and found out that Sheldon was in his room.
But neither Howard nor Raj wanted to get in to get Leonard's spare glasses where located in his room, dresser, next to bat signal.
Leonard can't help but doing it by himself with mini-cam and headset so that Howard and Raj can watch for him by remote laptop while he entered in.
Howard also handed a sub-sonic impact sensor to Leonard and told him it can register Sheldon's movement if he gets out of bed and starts to walk and send the signal back to Raj's laptop. but at the point of sensor's registering, Leonard only have less in 7 seconds to get out glasses or no glasses.
dresser: with drawers at down parts and mirror at the top
sub-sonic: very fast but not as fast as the speed of sound
register: official lists; measuring the scale or level of something such as sound
signal: gesture or sound with a particular message to someone
impact: something that has affected the second thing
