Gorgeous dog!
Looking at the dog's expression, (from my experience),
he is frustated and has build up panted energy inside of him.
German Shepherd is naturally a working dog and he need a thorough & consistant exercise regime + obedience training and as GSD is highly inteligent dog, he will get such frustration so that "too strong and energetic" is actually hyperactivity of a frustrated dog.
In addition, he is an intact 2 year old male - which means he is also frustrated with the growing hormone in him for being prevented from mating. In this case, i suggest he should be fixed or neutered to reduce the frustration - especially when there are females on-heat nearby. The urge of mating is natural instinct and it is only right for him to run away/run around or excessive barking tempted by the scent of on-heat females. This time he will get into aggression and will not listen to you - or may attack owner.
Anyway, neutering is also good for him if he is to be kept as companion or pet which means his agression will be reduced and prostrate cancer can be prevented and many more benefits actually.
Best of luck in finding him a good home - he is such a gorgeous dog and his hyperactivity can be fixed dont worry.

Yup agree.. Please neuter him before sending him to new home. Despite your friend best effort to choose the most suitable and legitimate adopter, in any event he runs loose or out of the house in the future he will not impregnate outside strays, orworse he could be pick up by unscrupulous people and use as breeding dog :)

Hi! thanks for all d nice comment! yes, my friend's one main condition is that the new owner must neuter ceasar...n she understand the character of a GSD..but unfortunately, her mum is too old now to handle him...she will be interviewing potential owner to ensure he is in good hands!

but d sad case of it is that i have a few calls immediately i posted this up...i just wish i will have d same respond for normal breed dogs...it seems hard to get those lovely normal breed dogs to get adopted...people perspective that pure breed is better is kinda sickening really...but that is just my tots tho..=)