Estar fumado, or grifo, it’s the Mexican slang way to say someone is on drugs or “high”.
Ser muy grifo is being huge into drugs.
You can also use “estar fumado” when someone says something ridiculous, or is doing something stupid, comparing his weird or uncommon actions with the ones of someone inhibited and affected by the usage of drugs.
Mi amigo probo la mariguana por primera vez, y se puso muy grifo. /My friend tried marihuana for the first time, and he got super high.
estas fumado! el precio al que vendes ese auto es demasiado alto/You are crazy! The price you are asking for that car is way to high.
I hope you have learned something new, about the spanish that real Mexicans talk on their everyday life.
If you want to improve your Spanish, I also give tutoring lessons on skype using this page that host many teachers from all over the world, and while I don’t really do grammar, I can help with conversation and doubts about the language. Also, if you are interested in any language besides spanish, there are teachers and tutors for any language there.