Keep it a hundred
Bun B, who did a verse on Jay-Z’s “Big Pimpin”, has a song called “Keep it a hundred”
“Keep it a hundred” can also mean “keep it real”, which would be the opposite of what Z100 keeps it, which is why this makes for a delightful pun (even though the advice seems odd coming from Kanye, who epitomizes rap-crossover success of the Z100 variety)