Here we go again, received another chainmail urban legend plying around, this time the hoax is about Coke + Ajinomoto / MSG (Mono Sodium Glutamate). This urban legend came about in the wild 2005 and was collected by Snopes around 2008. They call it the date rape drug but of course it won't work.
Although MSG (Mono Sodium Glutamate) may cause drowsiness, rapid heart rate, chest pain, nausea, weakness, difficulty in breathing, to certain people susceptible and sensitive to MSG, for the symptoms manifest for the unfavourable individuals large quantities of MSG amounting to about 3 grams or more need to be ingested. (A typical serving MSG treated food is less than 0.5 grams of MSG). However not all people are affected and only a small percentage are affected by MSG.
So regarding Canny Ong abduction, rape and murder case (13/June 2003), she was taken at knife point from Bangsar Shopping Centre basement car park and not from a spike drink. Besides, who would in the right mind accept a free drink offer from a stranger? A forced demand with a dangerous weapon such as a knife or gun is far more effective than trying to persuade a victim to take a spiked drink.
Source: http://www.snopes.com/cokelore/msg.asp
Anyway, I know friends are trying to mean well when they forward messages warning about this and that, but some of this has no truths behind it and some far too improbable that all you need to do is do quick check on the internet and you would know it is just a hoax started by somebody who thought it would be funny to scare the wits out of individuals who either didn't bother to verify the information or thought it sounded plausible but in fact just a bunch of baloney floating around cyberspace.
Perhaps he/she just wanted to see his urban legend creation get listed together with the rest of other urban legend for some anonymous hall of fame or what. This people really need something better to do if they got so much time in their hand to craft such urban legends like this Coke + Ajinomoto / MSG hoax.