Someone told me that staffordshire bull terriers heads crack as they grow. Is this true? And if so, what happens and at what age?

Ive never heard of this happening maybe someone will be along soon to confirm !

Its a term usually used to describe the head growth- it doesnt literally crack. Another term used by some is the "head splitting"

Does sound a bit alarming. Also known as "breaking" in some breeds - relates to the head maturing really, when the definition of the stop becomes more marked owing to the change in angles of the bones in the skull & foreface.