Yeah, I've never heard of that happening. All that might happen is they die/leave early because you fed them too many sweets. But not literally exploding.
Some friend. What a stinking liar! Your Tama won't blow up if you feed it too much! When you get to the point where it's not hungry anymore, it'll just refuse food! You might want to tell your friend this interesting little fact.
Your friend isn't telling the truth. Your tama won't explode, it may not want to eat anymore and shake it's head, or it may die at an early age. But i'm pretty sure they don't explode. ^^
i wouldn't believe that because i feed my tama a lot and it never explodes i tink u should just tell your friend i don't believe that but i still want to be friends