Here is the full list of all 22 Sex Standing achievements.
Dying for the first time
Deliver 1 consignment
Walk 1 km
Buy all guns
Upgrade all guns to maximum
Buy all perks
Upgrade all perks to maximum
Buy up the whole shop
Open all story scenes
Kill 10 enemies
Kill 50 enemies
Deliver 5 consignments
Deliver 10 consignments
Losing cargo for the first time
Build a bridge
Find the secret scene 1
Find the secret scene 2
Find the secret scene 3
Find the secret scene 4
Open all sex scenes
Walk 5 km
Walk 10 km