Here's some context from the film Scent of a Woman (1992), starring Al Pacino:
Lieutenant Colonel Frank Slade: The original bulging briefcase man. Gretchen, I smell those prunes! We talkin' Turkey Marbella?
Gretchen: Yes, we are, Frank.
Lieutenant Colonel Frank Slade: Ooh! Let's have a whiff. Come on. You know, I always had a sneaker for you. Come here. Where are you, Garry? I heard you cough.
What is the meaning of I always had a sneaker for you?
Colonel Slade is saying he has always been attracted to Gretchen (who is married to the Colonel's brother). He's using "sneaker" as vulgar slang for having an erection. I interpret the word as suggesting his erection is hidden by clothing, and other signs of his attraction are veiled by polite behavior - only to be exposed by his shocking words.
The lines "Where are you, Garry? I heard you cough." are not spoken to Gretchen, but rather to her youngest son, the Colonel's other nephew.
