The bulk update request #11459 is pending approval.

create alias little_penis (0) -> small_penis (23080)
create alias little_cock (0) -> small_penis (23080)
create alias thick_dick (2) -> thick_penis (41879)
create alias thick_shaft (21) -> thick_penis (41879)
create alias small_testicles (0) -> small_balls (4490)
create alias big_testicles (0) -> big_balls (242167)
create alias large_knot (5) -> big_knot (3930)
create alias large_sheath (26) -> big_sheath (2602)

Reason: A straightforward alias BUR covering synonyms of genital size tags.

Also includes thick_shaft despite shaft not being used elsewhere since it keeps getting tagged to describe thick penises:
https://e621.net/post_versions?commit=Search&search%5Btags_added%5D=thick_shaft