When someone is depressingly horny to the point of the exhaustion.
One may experience one or more of the following:
Obsession/fixation with one's own right hand
Frequent masturbation (~5-10 times a day)
Loss of appetite
Uneven arm strength
Shakiness when speaking to women
"Yo that dude hasn't gotten play in months, he must have Slappy Syndrome"
Another way of calling someone a dummy without being so blunt or without them catching on. Comes from "Slappy the Dummy" a ventriloquist dummy from the series goosebumps.
"Listen slappy, no one asked you for your opinion so why don't you fuck off?"
When your bro or a stranger is at an adjacent urinal and needs help with getting the dew off the lilies.
"Hey bro, you need slappies?" "Yeah man, you?" "Yeah." *slaps* *slaps* "Thanks!" "No problem!
When two men are at adjacent urinals, it is common courtesy to ask if the man next to you needs slappies. Slappies is when you assist another man with "shaking the dew off the lilies" so-to-speak. You slap the man's d*ck to get the last few drops of urine out for him. It is also common for the slappee to ask the slapper if he would like slappies as well.
"Hey bro, need slappies?" "Yeah." "Ok!" *slaps* "Thanks man, do you need slappies?" "Yeah." *Slaps* "Thanks man." "No problem!"