An act which is suspicious. From the words: Suspicious (sus) and Activity (tivity)
Typical black man walks by
Typical whie man: That's some sustivity right there
by fitnah March 8, 2020
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the level or measurement of how sus someone is
"ngl bro that guy over there is looking fine"

"damn bro how sus are you, your sustivity level is prolly over 9000"
by ShinyCynda August 19, 2022
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