A sexual position where you lay on your back with the girl penetrated on your chest. You then spin her around like a helicopter. I suppose you can do it in a variety of ways but you get the basic idea.
Sozacopter is another texting or IMing word like roflcopter.
It has become increasingly popular as it flies through the air faster than any lolplane could.
It is simply a cool way of saying soz and adding on the extra 'copter' at the end.
Showing that you are extremely sorry for what you have done/said.