Charlize Theron -- Kids With Sean Penn

Charlize Theron can play with her 2 year-old son without fear of hikers who jump to conclusions ... at least when she does it in the middle of Los Angeles.

The Oscar winning mom was out with BF Sean Penn yucking it up in front of the paparazzi.

We broke the story ... a hiker called 911 after hearing Jackson's screaming mid-temper tantrum Friday. Cops quickly realized the kid was fine and it was a false alarm.

This time there were only screams of joy.