Going through security at an airport or train station is stressful enough. What's even more stressful is when security mistakes your belt buckle for a weapon! In their defense, the belt buckle looks just like a hand grenade. Only when you flip it around can you tell it's a harmless belt buckle.
However, two main rail stations in Madrid and Barcelona had to be completely evacuated. The explosives unit was dispatched but all has been cleared once the suitcase was opened. Next time, maybe leave the grenade belt buckle at the house?