[Cruze]

PHP Code:

public void OnEntityCreated(int entity, const char[] classname)
{
    if(StrContains(classname, "_projectile") != -1) SDKHook(entity, SDKHook_SpawnPost, Grenade_SpawnPost);
    if(StrContains(classname, "_projectile") != -1) SDKHook(entity, SDKHook_StartTouch, Catch);
}

public void Grenade_SpawnPost(int entity)
{
    int client = GetEntPropEnt(entity, Prop_Send, "m_hOwnerEntity");
    if (client == -1)return; // if the client's index is -1, stop
    int iReference = EntIndexToEntRef(entity);
    CreateTimer(0.1, Timer_OnGrenadeCreated, iReference);
}

public Action Timer_OnGrenadeCreated(Handle timer, any ref)
{
    int entity = EntRefToEntIndex(ref);
    if(entity != INVALID_ENT_REFERENCE)
    {
        SetEntProp(entity, Prop_Data, "m_nNextThinkTick", -1); // block grenade explosion
        SetEntProp(entity, Prop_Send, "m_CollisionGroup", 5);
    }
}

public void Catch (int client, int entity)
{
    if (!IsValidEntity(entity))
        return;

    PrintToChatAll("the football has hit something");    
} 


Try this