Leonard started to enter the apartment with the way of being on his hands and knees, when he finally got close enough to Sheldon's room, Howard told him to deploy the sensor and turn it on. Leonard realized that he didn't really have to crawl, well, at least before turning the sensor on.
After the sensor is on, it is picking up somethi
ng and beeping, Howard told Leonard to turn his head to find out what is going on. Then they found out Penny standing in front of Leonard. So Howard and Raj ran away and left Leonard facing Penny alone.
Same thing happened when Penny found out Leonard's back, after she called Leonard a rat bastard. She left Leonard to deal with Sheldon alone.
bear: if you bear something somewhere, you take it there carefully.
bear a situation means to deal with it though you don't want to.
congested: if part of your body is congested, it is blocked
grill: cook something over a fire with a heated bar or frame.
deliberate: if you decide to do something in a deliberate way, you do it beforehand, so it happens on purpose rather than by chance.
rat: a kind of animal with a long tail looks like a large mouse.
if you call someone a rat, you disapprove of them because they go to someone in authority and tell them bad things that someone else does for getting something benefit.
deploy: to put or position something so it is ready to be used.
