There's finally enough pony ballbusting for making a dedicated thread for it!
Buttsaucer's furaffinity page: http://www.furaffinity.net/gallery/buttsaucer/
Majority of these come from the fchan thread here: http://fchan.us/toon/res/126436.html#i126436
Direct links:
http://fchan.us/src/toon_14450316364...ick_color2.jpg
http://fchan.us/src/toon_14450315059...olor_CANON.jpg
http://fchan.us/src/toon_14450315421...gic_color2.jpg
http://fchan.us/src/toon_14450314571...hack_color.jpg (M)
http://fchan.us/src/toon_14450315775...wing_smack.jpg
http://fchan.us/src/toon_14450316042...oods_color.jpg
http://fchan.us/src/toon_14450316680...ples_color.jpg
http://fchan.us/src/toon_14450316966...ange_color.jpg
http://fchan.us/src/toon_14450317217...y_expected.jpg
http://fchan.us/src/toon_14453760677...econd_pass.jpg
http://fchan.us/src/toon_14455294914...roin_boing.jpg
http://fchan.us/src/toon_14455444948...ing_by_now.jpg
http://fchan.us/src/toon_14451313324...ency_color.jpg
http://fchan.us/src/toon_14451667902...y_it_color.jpg (M)
http://fchan.us/src/toon_14451864708...a_bad_idea.jpg
http://fchan.us/src/toon_14452937189...et_swole_2.jpg
http://fchan.us/src/toon_14453222728...ies_Fetish.png
http://fchan.us/src/toon_14453398403...out_of_you.png
http://fchan.us/src/toon_14456032227...rn_edition.jpg (M/M)
http://fchan.us/src/toon_14456082371...this_right.jpg
http://fchan.us/src/toon_14456159399...w_too_much.jpg (M)
http://fchan.us/src/toon_14456277935...win_for_me.jpg (M)
http://fchan.us/src/toon_14456926895...e_Twilight.jpg
http://fchan.us/src/toon_1445704030025_Solid_Nuts.jpg
http://fchan.us/src/toon_14457956454...nd_squeeze.jpg
http://fchan.us/src/toon_14457980680...g_practice.jpg
http://fchan.us/src/toon_14459709653...r_I_quit_2.jpg
http://fchan.us/src/toon_14462163914...ght_damage.jpg
http://fchan.us/src/toon_14462218004...ristocrats.png
http://fchan.us/src/toon_14463890212..._for_years.jpg
http://fchan.us/src/toon_14463905849...oor_acting.jpg
http://fchan.us/src/toon_14465894223...fanfiction.png
http://fchan.us/src/toon_14468192876...killer_use.jpg
http://fchan.us/src/toon_14468196715...r_use_nude.jpg
http://fchan.us/src/toon_14468407313...ting_touch.jpg
http://fchan.us/src/toon_14469089329...the_guards.jpg
http://fchan.us/src/toon_14456004498...ts_earlier.jpg
http://fchan.us/src/toon_14453398403...out_of_you.png
http://fchan.us/src/toon_14469284997..._milkshake.jpg
http://fchan.us/src/toon_14470881193..._to_injury.jpg
http://fchan.us/src/toon_14470995477...in_a_prize.jpg
http://fchan.us/src/toon_14480311632...exy_at_all.jpg
http://fchan.us/src/toon_14482075361..._be_on_top.jpg
http://fchan.us/src/toon_14482320594...kes_apples.jpg
http://fchan.us/src/toon_14488210100...plateapple.jpg (M)
http://fchan.us/src/toon_14489752661...ack%5B1%5D.jpg
http://fchan.us/src/toon_1449176668610_Helping_hoof.jpg
http://fchan.us/src/toon_14492419646..._detention.jpg
http://fchan.us/src/toon_14493507536...ger_Perks2.jpg
http://fchan.us/src/toon_1449411426870_Flower_Trio.jpg
http://fchan.us/src/toon_14494117245..._Trio_nude.jpg
http://fchan.us/src/toon_14495840338...dominates2.jpg
http://fchan.us/src/toon_14498614954...gue%5B1%5D.png
http://fchan.us/src/toon_14502859804..._the_pants.jpg
http://fchan.us/src/toon_14509133911...ard%5B1%5D.jpg
http://fchan.us/src/toon_14509872041...ack%5B1%5D.png
http://fchan.us/src/toon_14531413670...ng_playful.jpg
http://fchan.us/src/toon_14531593967...ayful_nude.jpg
http://fchan.us/src/toon_14533957035..._Blueblood.jpg
http://fchan.us/src/toon_14535484306...blood_nude.jpg
http://fchan.us/src/toon_14537360467...ou_fuck_me.jpg
http://fchan.us/src/toon_14538944703...715%5B1%5D.jpg
http://fchan.us/src/toon_14539422477...ke_it_good.jpg
http://fchan.us/src/toon_14542867729...der%5B1%5D.jpg
http://fchan.us/src/toon_14547106379..._go_wrong2.jpg
http://fchan.us/src/toon_14547107730...ie_colors2.jpg
http://fchan.us/src/toon_14547109919...both_kids2.jpg
http://fchan.us/src/toon_14547112089..._nutshock2.jpg
http://fchan.us/src/toon_14547117452...k_shooter2.jpg
http://fchan.us/src/toon_14547118545...e_one_kid2.jpg
http://fchan.us/src/toon_14547120730...blestrike2.jpg
http://fchan.us/src/toon_14547123473..._you_a_boy.jpg
http://fchan.us/src/toon_14547128798...f_to_that2.jpg
https://derpicdn.net/img/view/2015/7...+crusaders.jpg
https://derpicdn.net/img/view/2015/7..._horsecock.png
https://derpicdn.net/img/view/2015/2...mpits_feet.png
https://derpicdn.net/img/view/2014/1...ls_bipedal.jpg
https://derpicdn.net/img/view/2014/9...ded_abuse.jpeg
https://derpicdn.net/img/view/2013/8...ope_femdom.png
https://derpicdn.net/img/view/2013/6...ll+busting.png
https://derpicdn.net/img/view/2013/3...ll+busting.jpg
https://derpicdn.net/img/view/2013/2...emans+pink.png
https://derpicdn.net/img/view/2012/1...on_femdom.jpeg
https://derpicdn.net/img/view/2012/1...oin+attack.jpg
https://derpicdn.net/img/view/2012/1..._horsecock.png
https://derpicdn.net/img/view/2012/6...ll+busting.png
http://fchan.us/src/toon_14547563184...638d309c3f.png
The genre always needs new ideas, so if you can think of new situations or ways a mare can hurt a stallion, please post them here. Stories and all other pony busting content and discussion are welcome as well.