Someone has an i-high for the first few weeks (or months if they're real douches) after purchasing an iphone. People on an i-high cannot physically keep their iphone in their pocket and fail to shut the fuck up about all their moronic and pointless apps. There is no cure for an i-high at this time, luckily it will wear off after a while when the person figures out the iphone is just an over-rated ipod with a phone crammed in it.
"Hey bro, check out this new app i just download from itu-"
"-You know what!! No, i refuse to look at your pointless iphone apps ever again! So why don't you just get the fuck off your i-high and get a life!"
noun: The elated feeling-one part refreshed, one part hip, and the rest Narcissistic-one receives upon downloading the newest (oh, wait...not anymore) version of Apple's operating system (for any device); the iHigh is directly followed by the iFail, or the inevitable realization of utter impotency in the face of Apple's conspiracy-not to mention a dangerously successful business model-to constantly outsmart its consumers, who nonetheless impulsively continue to purchase Apple products.
Man, when the App Store popped up with the iOS6 update that included Siri for the iPod touch, I got such an iHigh; then I realized that iFail...my iPod Touch 4th Gen. doesn't have the necessary hardware for Siri!