what does "lunge to one's feet"mean?
Without conscious thought she drove past her own house, slammed the brakes in front of Maureen’s.
Light. People. Safety.
She ran to the door, shoved it open, stopping only when she saw her friends snuggled up in front of the TV.
Both of them lunged to their feet.

Question

what does "lunge to one's feet"mean?
Without conscious thought she drove past her own house, slammed the brakes in front of Maureen’s. 
Light. People. Safety. 
She ran to the door, shoved it open, stopping only when she saw her friends snuggled up in front of the TV. 
Both of them lunged to their feet.

Answer

They stood up very quickly and with great energy.