Spend a life time being stoned all the time. Seriously, hardly anyone knows if I'm stoned or not, its just me being like I always am :)
Someone told me about crunching a pepper corn to get straight. I tried it once, but wouldn't recommend it! Vitamin C is the tested method that will help. If all else fails, feign an allergy reaction as these can cause red eyes and slowness of thought and being distracted, its your best bet for an explanation!