Eddie's Best Pick-up Riddle

I found the best riddle today on my A Year of Riddles app (great fun if you like riddles, are mildly obsessed with The Riddler or both). Maybe it's just my dirty mind but it instantly made me think of the kind of riddle Edward Nygma would use to pick up girls, showing his incredible genius and that he is capable of amazingly smutty double entendre (I'm sold).

Have a look:

I saw a strange creature:
Long, hard, and straight,
Thrusting into a round, dark opening,
Preparing to discharge its load of lives.
Puffing and squealing noises accompanied it,
Then a final screech as it slowed and stopped.

Do you guys know what it is? Leave a comment if you want to guess (don't cheat by googling it...anyone can do that...) and I'll tell you if you're right!