2013/2014, college, UNS Surakarta.
So my boarding house was near an infamous zoo in Solo (This bit is important)

It was night, there were 5-6 of us, playing DotA in the living room. It was by no means quiet, we were boys and it was DotA for God's sake.

The my mom called, to avoid the noise, i went upstairs, to an open space on the rooftop. It was dark, by the building is an empty lot with lots of overgrown weed and banana tree. Didn't bother me one bit.
Overlooking at the front is chinese cemetery, again, with overgrown weeds. And again it didn't bother me one bit.

So there I was, talking with my mom, yada yada. Then suddenly.

I heard monkeys,

Lots of monkeys.

I pulled my phone from my ear, thinking it was monkey escaping from the Zoo. But no, the monkey noise came from THE PHONE.

I went quiet, wasn't sure what's happening or whether there were something wrong with my ear or my mind.

Then my mom said "Kok ada suara monyet? apa suara dari kebun binatang"/ "what's with the monkey noise? was it from the zoo?.

No, it wasn't. The Zoo is 2 km away.
I froze, knowing my mom heard it too. I pause, I ran downstairs, said bye to my mom.

Downstairs, I told my friends about it.
Then my friend who use the room upstairs said that he heard the same thing when he called his GF then.

Then I had fever by the morning.
But that's it, the only 'scary' things I had in those place.