[art by firstname.lastname@example.org]
His pupils are not only dilated at seemingly all times (more on that later), they're unusually "fuzzy" in appearance, almost looking more like ink splotches rather than human pupils. They're framed by a large blue unibrow, adding to his variety of expressions. His tone and demeanor tend to swing between a deadpan/nihilistic attitude, and a more-out-of-control level of enthusiasm towards the subject he's currently addressing (usually either something vulgar in nature, or something endlessly praising himself).
Rick's mind is far too big and moving far too fast for his feeble human body, and that is reflected in both his demeanor and his quirks. It's rare to see a moment in which Rick is idle, as even when he's not particularly busy doing anything, his fingers seem to be constantly twitching or his eyes are darting about. It's part of why he numbs himself - and that's always reflected in the way he presents himself. Even when he's as sober as a priest, Rick's pupils are consistently diluted and the smell of alcohol radiates from him. A steady stream of drool will occasionally fall from his mouth and dribble on to his cheek, something that persists in-canon even when switches bodies with characters of another species.
But more importantly, his inebriation is reflected within his manner of speaking. Rick consistently trips over his own words, stuttering and drawing out certain syllables in what can only be described as a drunken slur. Occasionally, his rambling will be interrupted mid-sentence by an unprompted belch.
He smells exactly like you'd expect him to - either like alcohol or chemicals. He does tend to groom himself more often than not, of course, but it's usually ruined by his...Rickness.