11 Chickens in 35 seconds
/scoreboard objectives add drop stat.drop
/scoreboard objectives add boom dummy
/scoreboard objectives add chicken dummy
/scoreboard objectives add chicken2 stat.killEntity.Chicken
/execute @p[score_chicken2_min=1] ~ ~ ~ /summon Chicken ~ ~ ~15 {Attributes:[{Name:generic.maxHealth,Base:1},{Name:generic.movementSpeed,Base:0.01}]}
/clear @e[score_chicken2_min=1]
/scoreboard players set @p[score_chicken2_min=1] chicken2 0
/execute @p ~ ~ ~ fill ~1 ~ ~1 ~-1 ~ ~-1 air 0 replace fire
/execute @p[score_chicken=1,score_chicken_min=1] ~ ~ ~ /summon Item ~ ~ ~8 {Item:{id:minecraft:stick,Damage:0,Count:1}}
/scoreboard players set @p[score_chicken=1,score_chicken_min=1] chicken 2
/execute @p[score_flint_min=1] ~ ~ ~ scoreboard players add @e[r=1] chicken2 1
/execute @p[score_flint_min=1] ~ ~ ~ scoreboard players add @e[r=1] chicken 1
/scoreboard players set @p[score_flint_min=1] flint 0
/execute @e[name=unknown] ~ ~ ~ execute @e[type=Chicken,r=1] ~ ~ ~ scoreboard players add @p[score_chicken_min=18,score_chicken=18] chicken2 1
/execute @e[name=unknown] ~ ~ ~ execute @e[type=Chicken,r=1] ~ ~ ~ scoreboard players add @p[score_chicken_min=18,score_chicken=18] chicken 1
/execute @e[score_chicken_min=19,score_chicken=19] ~ ~ ~ execute @e[name=unknown] ~ ~ ~ kill @e[r=2]
/execute @p[score_drop_min=1] ~ ~ ~ scoreboard players add @e[type=Item] boom 1 {Item:{id:minecraft:tnt}}
/execute @e[score_boom_min=20,score_boom=20] ~ ~ ~ /summon Chicken ~ ~ ~15 {Attributes:[{Name:generic.maxHealth,Base:1},{Name:generic.movementSpeed,Base:0.01}]}
/execute @e[score_boom_min=20] ~ ~ ~ summon PrimedTnt
/scoreboard players set @p[score_drop_min=1] drop 0