I would suggest:

• 1KB = storage capacity of 1 kg of 1.44 floppy disks.
• 1MB = storage capacity of 0.0106 mile of CD drives.
• 1GB = storage capacity of 1 good computer in the 2000s.
• 1TB = storage capacity of 1 truck of GB (see above)

PS: just to be clear, I meant CD drives, not CD discs.