By now the pitifully few weapons of the Earthmen were popping.
The fellow, popping out his head, said, "Shall it be we then?"
There was a popping up of heads all over the school-room to get a sight of the picture.
Superdreadnoughts Were popping into existence at the rate of hundreds per minute.
They are as normal to me now as the popping of corn or the roasting of potatoes.