This happened a couple of weeks ago, I was just dropping of my sister and brother-in-law at Marriot Hotel in Newport City around 11:45 pm, so they could catch their morning flight back to abroad.
Normally I just take Dr. A. Santos Ave back Home but just to save a few minutes I just took the Skyway.
I got on and just right before the tollbooth, I noticed some exotics trailing on the E-Pass lane, Gallardo, Porsche 911, Audi R8, Nissan GTR, BMW M3 and a Lexus IS-F. After I got my fix on exotic automotive engineering and paid the toll, I saw the convoy fly by quickly but then....
They slowed down at about 70-80kph, the Nissan GTR turns it's hazards on and in front of it 3 cars lined-up the BMW, Lambo and Porsche, and I said to myself; you got to be kidding me, I'm currently witnessing exotics cars illegally drag racing on the highway(this is common in other countries like Germany or the US but here in Manila, they should try doing this in EDSA then I'll be impressed).
I just backed off and let them be, and as just seeing the thread marks they left on the asphalt. In the back of my mind I kept thinking what if something went wrong, like if one of them blew a tire and lost control they could end up killing themselves or other drivers on the highway like me. Too bad SLEX/Skyway doesn't have Speed Cameras or Radar Guns, I know the enforced speed limit is 100kph but 250+++ is excessive this is not the Autobahn if they're gonna play around they should do it in the track during the day.

I could've caught their plates but most of them had none the other one just had a PPSA vanity plate...

Update:
Youtubeland bears fruit; heres something very similar to what I witnessed:
http://www.youtube.com/watch?v=sWO87zmbsYo