Inopportune Erection

Not exactly sex related but kinda.

Sometimes when I do non-sexual things with my girlfriend, like hold her hand, pull her in close for a kiss or even spooning, I'll sometimes suddenly just get an erection. I do my best to hide it and have so far been successful, but its so damn awkward.

I am in my mid twenties and I am a virgin. Which I suppose is part of this problem. However that issue will be remedied next week when the gf gets back from being out of town.

Anyways, is there anything I can do to prevent these random erections and save myself potential embarrassment?