If it's centered around the middle line, it's known as an alto clef. If it's around the second line down, it's called a tenor clef. Fun, right? To my knowledge, after much searching, there are no standard mnemonics for these clefs. Therefore, invent!
For alto clef, I suggest you Forget Alto Clef Ever Got made. (That's the lines.) If that ticks the altos off, just remember that Girls of Beauty Delight in Flowers make up the spaces between.
In regards to the tenor, look at his lines and remark about his Dashing F-A-C-E. You can also remind him that Elegant Guys Bathe Daily are the spaces. (Those tenors!)
Have something better than my poor attempts? Do tell!