In the domain of street art, a jam means a legal event that brings together several graffiti artists. It was during a jam, bringing together 22 graffiti artists mainly from the Liège province, that the metal panels of this sports hall were painted. In addition to the different techniques used, several references, such as the extra-terrestrials taken from the Simpsons universe or the knight in armour drawn by J-Boy, are clear. On the contrary, the meaning of the expression Sept un fait (a play on words for the French for ‘it’s a fact’), which can be seen at several points, remains mysterious for the uninitiated.