use some variation of

crotch fabric tented outward, poking up, pulled tight away from his crotch

to get clothed boners.

examples generated using: pornmasterV2 checkpoint, ddim / sgm_uniform, 8 steps, cfg 1.

run between 0.7 and 1.5. directly mentioning cocks can make em poke out through the fly. turn the lora strength up higher to counter.