Mostly two:
Spheksophobia (fear of wasps) - When I was a little kid, we had a nest of tarantula hawks hornets in our garden and I got bitten by four of them before we knew they were there. Tarantula hawks stings are amongst the most painful in all the world (second only to the bullet ants stings), so I still remember the pain vividly to this day.
Acrophobia (fear of heights) - I suffer from a mild-to-severe case of vertigo which becomes rather proeminent whenever heights reach a large amount. Last summer I went camping with a couple of friends and my GF and we went trail-blazing through some rocky paths with very large jumps and falls....it took all my mental strength to get through them and that left me more exhausted than the actual jumping and walking about.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
