^^^^^^
That is 9mg of a very powerful benzo, which is a lot for someone that is not used to it. There are tonnes of threads here where people talk of taking even larger doses, many of those people are quite tolerant and often addicted to them.
I don't know what you guys were on but I have found that less can sometimes be more for getting sleep, take alot and you can easily wind up like one of your friends did kinda mashed and in limbo.
Follow SeveredPyche advice start low. Be aware that all benzo's are not equal, 1mg of clonazepam is equal to roughly 10mg of diazepam. Something alot of doctors even fail to grasp. In my experience they seem more than happy to prescribe me 1 or 2mg clonazepam but not 10 Mg Diazepam...go figure.
It is also important to remember that if mixing Benzo's with other drugs you need to use extreme caution...especially if any other CNS depressants are involved. Just because they are prescription drugs does not make them any safe.
Unlike K for example Benzo's can seriously depress your respiratory system.
If someone has had alot of alcohol or even a small amount of GHB/14b a dose like that could almost certainly result in a serious medical emergency.
Sorry if this post sounds preachy. I don't want to be a kill joy, just saying be aware and be informed. Take the time to read up how they work and their interactions. It is worth noting that while they work quickly it can take up to an hour for them to reach their maximum concentration in your blood so the effects can sneak up on you.
Taking that all into account IMO benzo's can be great for making a hard weekend land nice and softly. I've also had a bit of fun with them in LOW doses with a few beers (take it slow or you'll get totally shattered) and paradoxically found that this combo can even make you pretty chatty and energetic. Good old alprazolam (xanax) is probably the best, clonzaepam might be a bit to sedating. Great for talking utter crap with your friends and visiting planet memory loss.
That
www.benzo.org.uk is well worth the read. A lot of info about the various benzo & their drug profiles, medical uses and also tapered withdrawal schedules.