When you start doing squats so you can bob up and down in your "idle position" faster during "battle".
When you collect red things because they're probably made of dreamstone.
When you don't even care the V_translanka is being a cranky litl'un anymore.
When you start trying to pick up asphalt from the road because it has "item sparklies" all over it.
When you start to wander what the hell those old men are laughing about in the background of Magus' battle theme.
When you decide on a reasonable logical cause for the old man laughing in Magus' battle theme.
When you're tired, you start looking for your sword and item bag. (yes I know this from experience)
When you think you've solved the mysteries of life through talking to random people around your neighborhood.
When you suggest to someone to just go back and stop the (insert war here) from happening in the first place.
When you start pumping your fist, laughing, acting surpised, or spinning around in circles during music and call it "dancing".
When you try for hours to calculate the necessary physical conditions, fitness, velocity, and angle to execute a "Slash".
When you've written an email to Toryama Akira-sama, expressing your feelings about chrono trigger.
When you send it even after realizing A he doesn't really care, B he probably can't read your email anyway, and C he did it many years ago.
When you walk up to people and expect them to divulge their deepest secrets to you even though you haven even said anything.
When you start to think people can hear you nod your head.
When you begin to wonder why Marle is casting Fire Sword on the cover of the game.
EDIT: When you yell 'GRRRrrrrooooooooooooo" when you get into a fight and proceed to be flatulent at them...
EDIT2: When you start associating musicand background noise you hear around your house with Chrono Trigger every time you hear it because it happened once while you were playing. (Note I think of Chrono Trigger everytime I hear dogs barking, and think of Metal Gear Solid 3 whenever I hear Dragostea Din Tei)
EDIT the 3rd: When you have hours-long debates in your head about whether Magus is prunounces 'Mah' or 'May' gus.
When you claim Lavos or Entity as your religion on census forms.
When you think wearing 70's and 80's sunglasses make you stronger.
When you've tried Speed because you thought it would give you a yellow outline (this one was NOT me.)
When you have a t-shirt advertising "Norstein Beckler's amaaaazing show!"
When you were arrested for indecent exposure while trying to cosplay Norstein Bekkler (he doesn't have a body, so hence no clothes, again not me.)
When you wonder why people laugh when you talk about your swallow skills (well... sort of CC)((not me...))
When you wiki "swallow weapons thoughout history"
When you have more than 2 edits on a single post in this thread.
When you realize you'll have many more before anyone else even reads them.